Switch std::valarray<T> memory allocation to use std::__new_allocator<T>
to allocate and deallocate memory. This adds support for extended
alignment types without needing to duplicate all the logic from
__new_allocator::allocate and __new_allocator::dellocate.

std::__new_allocator is used instead of std::allocator because we want
to ensure that the memory is still allocated with operator new, so we
don't want to use any possible program-defined specialization of
std::allocator<T> which the user might have provided.

To make using an allocator possible, __valarray_release_memory needs to
become a function template so that it knows the type T. It also needs an
additional parameter specifying the size of the allocation.

This change doesn't cause an ABI change for types with fundamental
alignment, because __new_allocator still uses the same operator delete
function (or the sized version, which is ABI compatible) to free the
memory. So if memory for a valarray is allocated in one translation unit
and deallocated in another, and those TUs are compiled with different
versions of GCC, we still get memory from the same operator new and
release it with the same operator delete (or the compatibled sized
version). For types with extended alignment this does potentially cause
an ABI change on targets where the aligned version of operator delete
doesn't just call free(p), but support for extended alignment types was
previously just broken and had undefined behaviour.

libstdc++-v3/ChangeLog:

	PR libstdc++/108951
	* include/bits/valarray_array.h( __valarray_get_storage): Use
	std::__new_allocator.
	(__valarray_release_memory): Likewise.
	* include/std/valarray: Pass _M_size to
	__valarray_release_memory.
	* testsuite/26_numerics/valarray/108951.cc: New test.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>

In r15-3714-gd3a7302ec5985a I added -Wsystem-headers to the libstdc++ build
flags to help catch problems in the library.  This patch takes a different
approach, of disabling the #pragma system_header unless _GLIBCXX_SYSHDR is
defined.  As a result, the testsuites will treat them as non-system-headers
to get better warning coverage during regression testing of both gcc and
libstdc++, not just when building the library.

My rationale for the #ifdef instead of just removing the #pragma is the
three G++ tests that want to test libstdc++ system header behavior, so we
need a way to select it.

This doesn't affect installed libraries, as they get their
system-header status from the lookup path.  But testsuite_flags
--build-includes gives -I directives rather than -isystem.

This patch doesn't change the headers in config/ because I'm not compiling
with most of them, so won't see any warnings that need fixing.  Adjusting
them could happen later, or we can not bother.

libstdc++-v3/ChangeLog:

	* acinclude.m4 (WARN_FLAGS): Remove -Wsystem-headers.
	* configure: Regenerate.
	* include/bits/algorithmfwd.h: #ifdef out #pragma GCC system_header.
	* include/bits/atomic_base.h
	* include/bits/atomic_futex.h
	* include/bits/atomic_timed_wait.h
	* include/bits/atomic_wait.h
	* include/bits/basic_ios.h
	* include/bits/basic_string.h
	* include/bits/boost_concept_check.h
	* include/bits/char_traits.h
	* include/bits/charconv.h
	* include/bits/chrono.h
	* include/bits/chrono_io.h
	* include/bits/codecvt.h
	* include/bits/concept_check.h
	* include/bits/cpp_type_traits.h
	* include/bits/elements_of.h
	* include/bits/enable_special_members.h
	* include/bits/erase_if.h
	* include/bits/forward_list.h
	* include/bits/functional_hash.h
	* include/bits/gslice.h
	* include/bits/gslice_array.h
	* include/bits/hashtable.h
	* include/bits/indirect_array.h
	* include/bits/invoke.h
	* include/bits/ios_base.h
	* include/bits/iterator_concepts.h
	* include/bits/locale_classes.h
	* include/bits/locale_facets.h
	* include/bits/locale_facets_nonio.h
	* include/bits/localefwd.h
	* include/bits/mask_array.h
	* include/bits/max_size_type.h
	* include/bits/memory_resource.h
	* include/bits/memoryfwd.h
	* include/bits/move_only_function.h
	* include/bits/node_handle.h
	* include/bits/ostream_insert.h
	* include/bits/out_ptr.h
	* include/bits/parse_numbers.h
	* include/bits/postypes.h
	* include/bits/quoted_string.h
	* include/bits/range_access.h
	* include/bits/ranges_base.h
	* include/bits/refwrap.h
	* include/bits/sat_arith.h
	* include/bits/semaphore_base.h
	* include/bits/slice_array.h
	* include/bits/std_abs.h
	* include/bits/std_function.h
	* include/bits/std_mutex.h
	* include/bits/std_thread.h
	* include/bits/stl_iterator_base_funcs.h
	* include/bits/stl_iterator_base_types.h
	* include/bits/stl_tree.h
	* include/bits/stream_iterator.h
	* include/bits/streambuf_iterator.h
	* include/bits/stringfwd.h
	* include/bits/this_thread_sleep.h
	* include/bits/unique_lock.h
	* include/bits/uses_allocator_args.h
	* include/bits/utility.h
	* include/bits/valarray_after.h
	* include/bits/valarray_array.h
	* include/bits/valarray_before.h
	* include/bits/version.h
	* include/c_compatibility/fenv.h
	* include/c_compatibility/inttypes.h
	* include/c_compatibility/stdint.h
	* include/decimal/decimal.h
	* include/experimental/bits/net.h
	* include/experimental/bits/shared_ptr.h
	* include/ext/aligned_buffer.h
	* include/ext/alloc_traits.h
	* include/ext/atomicity.h
	* include/ext/concurrence.h
	* include/ext/numeric_traits.h
	* include/ext/pod_char_traits.h
	* include/ext/pointer.h
	* include/ext/stdio_filebuf.h
	* include/ext/stdio_sync_filebuf.h
	* include/ext/string_conversions.h
	* include/ext/type_traits.h
	* include/ext/vstring.h
	* include/ext/vstring_fwd.h
	* include/ext/vstring_util.h
	* include/parallel/algorithmfwd.h
	* include/parallel/numericfwd.h
	* include/tr1/functional_hash.h
	* include/tr1/hashtable.h
	* include/tr1/random.h
	* libsupc++/exception.h
	* libsupc++/hash_bytes.h
	* include/bits/basic_ios.tcc
	* include/bits/basic_string.tcc
	* include/bits/fstream.tcc
	* include/bits/istream.tcc
	* include/bits/locale_classes.tcc
	* include/bits/locale_facets.tcc
	* include/bits/locale_facets_nonio.tcc
	* include/bits/ostream.tcc
	* include/bits/sstream.tcc
	* include/bits/streambuf.tcc
	* include/bits/string_view.tcc
	* include/bits/version.tpl
	* include/experimental/bits/string_view.tcc
	* include/ext/pb_ds/detail/resize_policy/hash_prime_size_policy_imp.hpp
	* include/ext/random.tcc
	* include/ext/vstring.tcc
	* include/tr2/bool_set.tcc
	* include/tr2/dynamic_bitset.tcc
	* include/bits/c++config
	* include/c/cassert
	* include/c/cctype
	* include/c/cerrno
	* include/c/cfloat
	* include/c/ciso646
	* include/c/climits
	* include/c/clocale
	* include/c/cmath
	* include/c/csetjmp
	* include/c/csignal
	* include/c/cstdarg
	* include/c/cstddef
	* include/c/cstdio
	* include/c/cstdlib
	* include/c/cstring
	* include/c/ctime
	* include/c/cuchar
	* include/c/cwchar
	* include/c/cwctype
	* include/c_global/cassert
	* include/c_global/ccomplex
	* include/c_global/cctype
	* include/c_global/cerrno
	* include/c_global/cfenv
	* include/c_global/cfloat
	* include/c_global/cinttypes
	* include/c_global/ciso646
	* include/c_global/climits
	* include/c_global/clocale
	* include/c_global/cmath
	* include/c_global/csetjmp
	* include/c_global/csignal
	* include/c_global/cstdalign
	* include/c_global/cstdarg
	* include/c_global/cstdbool
	* include/c_global/cstddef
	* include/c_global/cstdint
	* include/c_global/cstdio
	* include/c_global/cstdlib
	* include/c_global/cstring
	* include/c_global/ctgmath
	* include/c_global/ctime
	* include/c_global/cuchar
	* include/c_global/cwchar
	* include/c_global/cwctype
	* include/c_std/cassert
	* include/c_std/cctype
	* include/c_std/cerrno
	* include/c_std/cfloat
	* include/c_std/ciso646
	* include/c_std/climits
	* include/c_std/clocale
	* include/c_std/cmath
	* include/c_std/csetjmp
	* include/c_std/csignal
	* include/c_std/cstdarg
	* include/c_std/cstddef
	* include/c_std/cstdio
	* include/c_std/cstdlib
	* include/c_std/cstring
	* include/c_std/ctime
	* include/c_std/cuchar
	* include/c_std/cwchar
	* include/c_std/cwctype
	* include/debug/array
	* include/debug/bitset
	* include/debug/deque
	* include/debug/forward_list
	* include/debug/list
	* include/debug/map
	* include/debug/set
	* include/debug/string
	* include/debug/unordered_map
	* include/debug/unordered_set
	* include/debug/vector
	* include/decimal/decimal
	* include/experimental/algorithm
	* include/experimental/any
	* include/experimental/array
	* include/experimental/buffer
	* include/experimental/chrono
	* include/experimental/contract
	* include/experimental/deque
	* include/experimental/executor
	* include/experimental/filesystem
	* include/experimental/forward_list
	* include/experimental/functional
	* include/experimental/internet
	* include/experimental/io_context
	* include/experimental/iterator
	* include/experimental/list
	* include/experimental/map
	* include/experimental/memory
	* include/experimental/memory_resource
	* include/experimental/net
	* include/experimental/netfwd
	* include/experimental/numeric
	* include/experimental/propagate_const
	* include/experimental/ratio
	* include/experimental/regex
	* include/experimental/scope
	* include/experimental/set
	* include/experimental/socket
	* include/experimental/string
	* include/experimental/string_view
	* include/experimental/synchronized_value
	* include/experimental/system_error
	* include/experimental/timer
	* include/experimental/tuple
	* include/experimental/type_traits
	* include/experimental/unordered_map
	* include/experimental/unordered_set
	* include/experimental/vector
	* include/ext/algorithm
	* include/ext/cmath
	* include/ext/functional
	* include/ext/iterator
	* include/ext/memory
	* include/ext/numeric
	* include/ext/random
	* include/ext/rb_tree
	* include/ext/rope
	* include/parallel/algorithm
	* include/std/algorithm
	* include/std/any
	* include/std/array
	* include/std/atomic
	* include/std/barrier
	* include/std/bit
	* include/std/bitset
	* include/std/charconv
	* include/std/chrono
	* include/std/codecvt
	* include/std/complex
	* include/std/concepts
	* include/std/condition_variable
	* include/std/coroutine
	* include/std/deque
	* include/std/execution
	* include/std/expected
	* include/std/filesystem
	* include/std/format
	* include/std/forward_list
	* include/std/fstream
	* include/std/functional
	* include/std/future
	* include/std/generator
	* include/std/iomanip
	* include/std/ios
	* include/std/iosfwd
	* include/std/iostream
	* include/std/istream
	* include/std/iterator
	* include/std/latch
	* include/std/limits
	* include/std/list
	* include/std/locale
	* include/std/map
	* include/std/memory
	* include/std/memory_resource
	* include/std/mutex
	* include/std/numbers
	* include/std/numeric
	* include/std/optional
	* include/std/ostream
	* include/std/print
	* include/std/queue
	* include/std/random
	* include/std/ranges
	* include/std/ratio
	* include/std/regex
	* include/std/scoped_allocator
	* include/std/semaphore
	* include/std/set
	* include/std/shared_mutex
	* include/std/span
	* include/std/spanstream
	* include/std/sstream
	* include/std/stack
	* include/std/stacktrace
	* include/std/stdexcept
	* include/std/streambuf
	* include/std/string
	* include/std/string_view
	* include/std/syncstream
	* include/std/system_error
	* include/std/text_encoding
	* include/std/thread
	* include/std/tuple
	* include/std/type_traits
	* include/std/typeindex
	* include/std/unordered_map
	* include/std/unordered_set
	* include/std/utility
	* include/std/valarray
	* include/std/variant
	* include/std/vector
	* include/std/version
	* include/tr1/array
	* include/tr1/cfenv
	* include/tr1/cinttypes
	* include/tr1/cmath
	* include/tr1/complex
	* include/tr1/cstdbool
	* include/tr1/cstdint
	* include/tr1/cstdio
	* include/tr1/cstdlib
	* include/tr1/cwchar
	* include/tr1/cwctype
	* include/tr1/functional
	* include/tr1/memory
	* include/tr1/random
	* include/tr1/regex
	* include/tr1/tuple
	* include/tr1/type_traits
	* include/tr1/unordered_map
	* include/tr1/unordered_set
	* include/tr1/utility
	* include/tr2/bool_set
	* include/tr2/dynamic_bitset
	* include/tr2/type_traits
	* libsupc++/atomic_lockfree_defines.h
	* libsupc++/compare
	* libsupc++/cxxabi.h
	* libsupc++/cxxabi_forced.h
	* libsupc++/cxxabi_init_exception.h
	* libsupc++/exception
	* libsupc++/initializer_list
	* libsupc++/new
	* libsupc++/typeinfo: Likewise.
	* testsuite/20_util/ratio/operations/ops_overflow_neg.cc
	* testsuite/23_containers/array/tuple_interface/get_neg.cc
	* testsuite/23_containers/vector/cons/destructible_debug_neg.cc
	* testsuite/24_iterators/operations/prev_neg.cc
	* testsuite/ext/type_traits/add_unsigned_floating_neg.cc
	* testsuite/ext/type_traits/add_unsigned_integer_neg.cc
	* testsuite/ext/type_traits/remove_unsigned_floating_neg.cc
	* testsuite/ext/type_traits/remove_unsigned_integer_neg.cc: Adjust
	line numbers.

gcc/testsuite/ChangeLog

	* g++.dg/analyzer/fanalyzer-show-events-in-system-headers-default.C
	* g++.dg/analyzer/fanalyzer-show-events-in-system-headers-no.C
	* g++.dg/diagnostic/disable.C: #define _GLIBCXX_SYSHDR.

The call to __valarray_copy constructs an _Array object to refer to
this->_M_data but that means that accesses to this->_M_data are through
a restrict-qualified pointer. This leads to undefined behaviour when
copying from an _Expr object that actually aliases this->_M_data.

Replace the call to __valarray_copy with a plain loop. I think this
removes the only use of that overload of __valarray_copy, so it could
probably be removed. I haven't done that here.

libstdc++-v3/ChangeLog:

	PR libstdc++/99117
	* include/std/valarray (valarray::operator=(const _Expr&)):
	Use loop to copy instead of __valarray_copy with _Array.
	* testsuite/26_numerics/valarray/99117.cc: New test.

libstdc++-v3/ChangeLog:

	* include/bits/shared_ptr_atomic.h (atomic): Change class-head
	to struct.
	* include/bits/stl_tree.h (_Rb_tree_merge_helper): Change
	class-head to struct in friend declaration.
	* include/std/chrono (tzdb_list::_Node): Likewise.
	* include/std/future (_Task_state_base, _Task_state): Likewise.
	* include/std/scoped_allocator (__inner_type_impl): Likewise.
	* include/std/valarray (_BinClos, _SClos, _GClos, _IClos)
	(_ValFunClos, _RefFunClos): Change class-head to struct.

Including the header source code in the doxygen-generated PDF file makes
it too large, and causes pdflatex to run out of memory. If we only set
SOURCE_BROWSER=YES for the HTML docs then we won't include the sources
in the PDF file.

There are several macros defined for std::valarray that are only used to
generate repetitive code and then #undef'd. Those aren't useful in the
doxygen docs, especially the ones that reuse the same name in different
files. Omitting them avoids warnings about duplicate labels in the
refman.tex file.

libstdc++-v3/ChangeLog:

	* doc/doxygen/user.cfg.in (SOURCE_BROWSER): Only set to YES for
	HTML docs.
	* include/bits/gslice_array.h (_DEFINE_VALARRAY_OPERATOR): Omit
	from doxygen docs.
	* include/bits/indirect_array.h (_DEFINE_VALARRAY_OPERATOR):
	Likewise.
	* include/bits/mask_array.h (_DEFINE_VALARRAY_OPERATOR):
	Likewise.
	* include/bits/slice_array.h (_DEFINE_VALARRAY_OPERATOR):
	Likewise.
	* include/std/valarray (_DEFINE_VALARRAY_UNARY_OPERATOR)
	(_DEFINE_VALARRAY_AUGMENTED_ASSIGNMENT)
	(_DEFINE_VALARRAY_EXPR_AUGMENTED_ASSIGNMENT)
	(_DEFINE_BINARY_OPERATOR): Likewise.

Add assertions to diagnose incorrect uses of valarray masks.

The assignment operators of std::mask_array do not have any explicit
preconditions in the standard, but the assignment operator
valarray<T>::operator=(const mask_array<T>&) requires the lengths to
match, so it seems consistent to also require that when the operands are
reversed.  In support of that interpretation, libstdc++ has undefined
behaviour if the right-hand operand has more elements than are selected
by the mask, and libc++ has undefined behaviour if it has fewer
elements. Our std::mask_array stores the number of selected elements as
_M_sz so it's easy to add an assertion that checks it.

For the valarray::operator[] that takes a valarray<bool> mask,
[valarray.sub] in the standard says: "In each case the selected
element(s) shall exist." This makes it undefined to have a mask that
refers to out-of-range elements. We can easily check this too.

libstdc++-v3/ChangeLog:

	PR libstdc++/62196
	* include/bits/mask_array.h (mask_array): Add assertions to
	assignment operators.
	* include/std/valarray (valarray::operator[](valarray<bool>)):
	Add assertions.
	* testsuite/26_numerics/valarray/mask-1_neg.cc: New test.
	* testsuite/26_numerics/valarray/mask-2_neg.cc: New test.
	* testsuite/26_numerics/valarray/mask-3_neg.cc: New test.
	* testsuite/26_numerics/valarray/mask-4_neg.cc: New test.
	* testsuite/26_numerics/valarray/mask-5_neg.cc: New test.
	* testsuite/26_numerics/valarray/mask-6_neg.cc: New test.
	* testsuite/26_numerics/valarray/mask-7_neg.cc: New test.
	* testsuite/26_numerics/valarray/mask-8_neg.cc: New test.
	* testsuite/26_numerics/valarray/mask.cc: New test.

PR libstdc++/103626 - _GLIBCXX_HOSTED should respect -ffreestanding

Co-authored-by: Jonathan Wakely <jwakely@redhat.com>

libstdc++-v3/ChangeLog:

	PR libstdc++/103626
	* include/Makefile.am: Add new header.
	* include/Makefile.in: Regenerate.
	* include/bits/requires_hosted.h: New header.
	* include/experimental/algorithm: Include
	<bits/requires_hosted.h>.
	* include/experimental/any: Likewise.
	* include/experimental/array: Likewise.
	* include/experimental/buffer: Likewise.
	* include/experimental/chrono: Likewise.
	* include/experimental/deque: Likewise.
	* include/experimental/executor: Likewise.
	* include/experimental/filesystem: Likewise.
	* include/experimental/forward_list: Likewise.
	* include/experimental/functional: Likewise.
	* include/experimental/internet: Likewise.
	* include/experimental/io_context: Likewise.
	* include/experimental/iterator: Likewise.
	* include/experimental/list: Likewise.
	* include/experimental/map: Likewise.
	* include/experimental/memory: Likewise.
	* include/experimental/memory_resource: Likewise.
	* include/experimental/net: Likewise.
	* include/experimental/netfwd: Likewise.
	* include/experimental/numeric: Likewise.
	* include/experimental/optional: Likewise.
	* include/experimental/propagate_const: Likewise.
	* include/experimental/random: Likewise.
	* include/experimental/ratio: Likewise.
	* include/experimental/regex: Likewise.
	* include/experimental/scope: Likewise.
	* include/experimental/set: Likewise.
	* include/experimental/simd: Likewise.
	* include/experimental/socket: Likewise.
	* include/experimental/source_location: Likewise.
	* include/experimental/string: Likewise.
	* include/experimental/string_view: Likewise.
	* include/experimental/system_error: Likewise.
	* include/experimental/timer: Likewise.
	* include/experimental/tuple: Likewise.
	* include/experimental/unordered_map: Likewise.
	* include/experimental/unordered_set: Likewise.
	* include/experimental/utility: Likewise.
	* include/experimental/vector: Likewise.
	* include/std/barrier: Likewise.
	* include/std/chrono: Likewise.
	* include/std/condition_variable: Likewise.
	* include/std/deque: Likewise.
	* include/std/execution: Likewise.
	* include/std/filesystem: Likewise.
	* include/std/forward_list: Likewise.
	* include/std/fstream: Likewise.
	* include/std/future: Likewise.
	* include/std/iomanip: Likewise.
	* include/std/ios: Likewise.
	* include/std/iosfwd: Likewise.
	* include/std/iostream: Likewise.
	* include/std/istream: Likewise.
	* include/std/latch: Likewise.
	* include/std/list: Likewise.
	* include/std/locale: Likewise.
	* include/std/map: Likewise.
	* include/std/memory_resource: Likewise.
	* include/std/mutex: Likewise.
	* include/std/ostream: Likewise.
	* include/std/queue: Likewise.
	* include/std/random: Likewise.
	* include/std/regex: Likewise.
	* include/std/semaphore: Likewise.
	* include/std/set: Likewise.
	* include/std/shared_mutex: Likewise.
	* include/std/spanstream: Likewise.
	* include/std/sstream: Likewise.
	* include/std/stack: Likewise.
	* include/std/stacktrace: Likewise.
	* include/std/stop_token: Likewise.
	* include/std/streambuf: Likewise.
	* include/std/string: Likewise.
	* include/std/syncstream: Likewise.
	* include/std/system_error: Likewise.
	* include/std/thread: Likewise.
	* include/std/unordered_map: Likewise.
	* include/std/unordered_set: Likewise.
	* include/std/valarray: Likewise.
	* include/std/vector: Likewise.
	* include/tr1/array: Likewise.
	* include/tr1/ccomplex: Likewise.
	* include/tr1/cctype: Likewise.
	* include/tr1/cfenv: Likewise.
	* include/tr1/cfloat: Likewise.
	* include/tr1/cinttypes: Likewise.
	* include/tr1/climits: Likewise.
	* include/tr1/cmath: Likewise.
	* include/tr1/complex: Likewise.
	* include/tr1/complex.h: Likewise.
	* include/tr1/cstdarg: Likewise.
	* include/tr1/cstdbool: Likewise.
	* include/tr1/cstdint: Likewise.
	* include/tr1/cstdio: Likewise.
	* include/tr1/cstdlib: Likewise.
	* include/tr1/ctgmath: Likewise.
	* include/tr1/ctime: Likewise.
	* include/tr1/ctype.h: Likewise.
	* include/tr1/cwchar: Likewise.
	* include/tr1/cwctype: Likewise.
	* include/tr1/fenv.h: Likewise.
	* include/tr1/float.h: Likewise.
	* include/tr1/functional: Likewise.
	* include/tr1/inttypes.h: Likewise.
	* include/tr1/limits.h: Likewise.
	* include/tr1/math.h: Likewise.
	* include/tr1/memory: Likewise.
	* include/tr1/random: Likewise.
	* include/tr1/regex: Likewise.
	* include/tr1/stdarg.h: Likewise.
	* include/tr1/stdbool.h: Likewise.
	* include/tr1/stdint.h: Likewise.
	* include/tr1/stdio.h: Likewise.
	* include/tr1/stdlib.h: Likewise.
	* include/tr1/tgmath.h: Likewise.
	* include/tr1/tuple: Likewise.
	* include/tr1/type_traits: Likewise.
	* include/tr1/unordered_map: Likewise.
	* include/tr1/unordered_set: Likewise.
	* include/tr1/utility: Likewise.
	* include/tr1/wchar.h: Likewise.
	* include/tr1/wctype.h: Likewise.
	* include/c_global/cmath: Likewise.
	* include/ext/algorithm: Include <bits/requires_hosted.h>.
	* include/ext/bitmap_allocator.h: Likewise.
	* include/ext/cmath: Likewise.
	* include/ext/codecvt_specializations.h: Likewise.
	* include/ext/debug_allocator.h: Likewise.
	* include/ext/enc_filebuf.h: Likewise.
	* include/ext/extptr_allocator.h: Likewise.
	* include/ext/functional: Likewise.
	* include/ext/malloc_allocator.h: Likewise.
	* include/ext/memory: Likewise.
	* include/ext/mt_allocator.h: Likewise.
	* include/ext/new_allocator.h: Likewise.
	* include/ext/numeric: Likewise.
	* include/ext/pod_char_traits.h: Likewise.
	* include/ext/pool_allocator.h: Likewise.
	* include/ext/random: Likewise.
	* include/ext/random.tcc: Likewise.
	* include/ext/rb_tree: Likewise.
	* include/ext/rc_string_base.h: Likewise.
	* include/ext/rope: Likewise.
	* include/ext/ropeimpl.h: Likewise.
	* include/ext/slist: Likewise.
	* include/ext/sso_string_base.h: Likewise.
	* include/ext/stdio_filebuf.h: Likewise.
	* include/ext/stdio_sync_filebuf.h: Likewise.
	* include/ext/string_conversions.h: Likewise.
	* include/ext/throw_allocator.h: Likewise.
	* include/ext/vstring.h: Likewise.
	* include/ext/vstring.tcc: Likewise.
	* include/ext/vstring_fwd.h: Likewise.
	* include/ext/vstring_util.h: Likewise.
	* include/std/charconv: Likewise.
	(__cpp_lib_to_chars): Do not define for freestanding.
	* include/std/version: Adjust which macros get defined in
	freestanding.
	* include/ext/pointer.h [!_GLIBCXX_HOSTED]: Omit iostream
	functionality from freestanding.
	* include/std/algorithm [!_GLIBCXX_HOSTED]: Omit PSTL algos.
	* include/std/memory [!_GLIBCXX_HOSTED]: Omit
	<bits/stl_tempbuf.h> in freestanding
	* include/bits/algorithmfwd.h [!_GLIBCXX_HOSTED]: Omit leftover
	random_shuffle and stable_partition definition.
	* include/bits/stl_algo.h [!_GLIBCXX_HOSTED]: Omit
	random_shuffle and stable_partition from freestanding.
	* include/bits/ranges_algo.h [!_GLIBCXX_HOSTED]: Omit
	stable_partition from freestanding.
	* include/bits/concept_check.h: Remove needless HOSTED check.
	* include/std/iterator: Include <bits/ranges_base.h>.
	* include/std/numeric (__cpp_lib_parallel_algorithms): Do not
	define for freestanding.
	* include/std/functional (__cpp_lib_boyer_moore_searcher):
	Likewise.
	* testsuite/lib/prune.exp: Match error for hosted-only libstdc++
	tests.