As discussed in bug 28327, C23 changed the fromfp functions to return
floating types instead of intmax_t / uintmax_t.  (Although the
motivation in N2548 was reducing the use of intmax_t in library
interfaces, the new version does have the advantage of being able to
specify arbitrary integer widths for e.g. assigning the result to a
_BitInt, as well as being able to indicate an error case in-band with
a NaN return.)

As with other such changes from interfaces introduced in TS 18661,
implement the new types as a replacement for the old ones, with the
old functions remaining as compat symbols but not supported as an API.
The test generator used for many of the tests is updated to handle
both versions of the functions.

Tested for x86_64 and x86, and with build-many-glibcs.py.

Also tested tgmath tests for x86_64 with GCC 7 to make sure that the
modified case for older compilers in <tgmath.h> does work.

Also tested for powerpc64le to cover the ldbl-128ibm implementation
and the other things that are handled differently for that
configuration.  The new tests fail for ibm128, but all the failures
relate to incorrect signs of zero results and turn out to arise from
bugs in the underlying roundl, ceill, truncl and floorl
implementations that I've reported in bug 33623, rather than
indicating any bug in the actual new implementation of the functions
for that format.  So given fixes for those functions (which shouldn't
be hard, and of course should add to the tests for those functions
rather than relying only on indirect testing via fromfp), the fromfp
tests should start passing for ibm128 as well.

As discussed in bug 28327, the fromfp functions changed type in C23
(compared to the version in TS 18661-1); they now return the same type
as the floating-point argument, instead of intmax_t / uintmax_t.

As with other such incompatible changes compared to the initial TS
18661 versions of interfaces (the types of totalorder functions, in
particular), it seems appropriate to support only the new version as
an API, not the old one (although many programs written for the old
API might in fact work wtih the new one as well).  Thus, the existing
implementations should become compat symbols.  They are sufficiently
different from how I'd expect to implement the new version that using
separate implementations in separate files is more convenient than
trying to share code, and directly sharing testcases would be
problematic as well.

Rename the existing fromfp implementation and test files to names
reflecting how they're intended to become compat symbols, so freeing
up the existing filenames for a subsequent implementation of the C23
versions of these functions (which is the point at which the existing
implementations would actually become compat symbols).

gen-fromfp-tests.py and gen-fromfp-tests-inputs are not renamed; I
think it will make sense to adapt the test generator to be able to
generate most tests for both versions of the functions (with extra
test inputs added that are only of interest with the C23 version).
The ldbl-opt/nldbl-* files are also not renamed; since those are for a
static only library, no compat versions are needed, and they'll just
have their contents changed when the C23 version is implemented.

Tested for x86_64, and with build-many-glibcs.py.

I used these shell commands:

../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")

and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.

I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah.  I don't
know why I run into these diagnostics whereas others evidently do not.

remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines

I used these shell commands:

../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")

and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master

Also, change sources.redhat.com to sourceware.org.
This patch was automatically generated by running the following shell
script, which uses GNU sed, and which avoids modifying files imported
from upstream:

sed -ri '
  s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g
  s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g
' \
  $(find $(git ls-files) -prune -type f \
      ! -name '*.po' \
      ! -name 'ChangeLog*' \
      ! -path COPYING ! -path COPYING.LIB \
      ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \
      ! -path manual/texinfo.tex ! -path scripts/config.guess \
      ! -path scripts/config.sub ! -path scripts/install-sh \
      ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \
      ! -path INSTALL ! -path  locale/programs/charmap-kw.h \
      ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \
      ! '(' -name configure \
            -execdir test -f configure.ac -o -f configure.in ';' ')' \
      ! '(' -name preconfigure \
            -execdir test -f preconfigure.ac ';' ')' \
      -print)

and then by running 'make dist-prepare' to regenerate files built
from the altered files, and then executing the following to cleanup:

  chmod a+x sysdeps/unix/sysv/linux/riscv/configure
  # Omit irrelevant whitespace and comment-only changes,
  # perhaps from a slightly-different Autoconf version.
  git checkout -f \
    sysdeps/csky/configure \
    sysdeps/hppa/configure \
    sysdeps/riscv/configure \
    sysdeps/unix/sysv/linux/csky/configure
  # Omit changes that caused a pre-commit check to fail like this:
  # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines
  git checkout -f \
    sysdeps/powerpc/powerpc64/ppc-mcount.S \
    sysdeps/unix/sysv/linux/s390/s390-64/syscall.S
  # Omit change that caused a pre-commit check to fail like this:
  # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline
  git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S

	* All files with FSF copyright notices: Update copyright dates
	using scripts/update-copyrights.
	* locale/programs/charmap-kw.h: Regenerated.
	* locale/programs/locfile-kw.h: Likewise.