This PR changes `getGlobalIdentifier()` into `getName()` value when
creating a name of a global variable, and fixes generation of
LinkageAttributes decoration of global variables by taking into account
Private Linkage in addition to Internal.

Previous implementation led to an issue with back translation of SPIR-V
to LLVM IR, e.g.:

```
@__const.G1 = private unnamed_addr addrspace(1) constant %my_type undef
...
Fails to verify module: 'common' global may not be marked constant!
ptr addrspace(1) @"llvm-link;__const.G1"
```

A reproducer is included as a new test case.

This PR fixes https://github.com/llvm/llvm-project/issues/120078 and
improves/simplifies parsing of demangled function name that aims to
detect a tip for floating point decorations. The latter improvement
fixes also a complaint from `LLVM_USE_SANITIZER=Address`.

This PR adds the following features:
* saturation and float rounding mode decorations,
* arithmetic constrained floating-point intrinsics (strict_fadd,
strict_fsub, strict_fmul, strict_fdiv, strict_frem, strict_fma and
strict_fldexp),
* and SPV_INTEL_float_controls2 extension,
* using recent improvements of emit-intrinsics step, this PR also
simplifies pre- and post-legalizer steps and improves instruction
selection.

This PR is to fix the following issues:
* the SPIR-V Backend didn't generate Alignment decoration for alloca
instructions,
* we need to use types from demangled function declarations to specify
types for opaque pointers.

This PR fixes:
* emission of OpNames (added newly inserted internal intrinsics and
basic blocks)
* emission of function attributes (SRet is added)
* implementation of SPV_INTEL_optnone so that it emits OptNoneINTEL
Function Control flag, and add implementation of the SPV_EXT_optnone
SPIR-V extension.

This PR resolved the following issues:
(1) There are rare but possible cases when there are bitcasts between
pointers intertwined in a sophisticated way with loads, stores, function
calls and other instructions that are part of type deduction. In this
case we must account for inserted bitcasts between pointers rather than
just ignore them.
(2) Null pointers have the same constant representation but different
types. Type info from Intrinsic::spv_track_constant() refers to the
opaque (untyped) pointer, so that each MF/v-reg pair would fall into the
same Const record in Duplicate Tracker and would be represented by a
single OpConstantNull instruction, unless we use precise pointee type
info. We must be able to distinguish one constant (null) pointer from
another to avoid generating invalid code with inconsistent types of
operands.

Goals of the PR are:
* to ensure that correct types are applied to virtual registers which
were used as return values in call lowering. A reproducer is attached as
a new test case, before the PR it fails because spirv-val considers
output invalid due to wrong result/operand types in OpPhi's;
* improve type inference by speeding up postprocessing of types: by
limiting iterations by checking what remains to process, and processing
each instruction just once for any number of operands with uncomplete
types;
* improve type inference by more accurate work with uncomplete types
(pass uncomplete property to dependent operands, ensure consistency of
uncomplete-types data structure);
* change processing order and add traversing of PHI nodes when type
inference apply instructions results to specify/update/cast operands
type (fixes an issue with OpPhi's result type mismatch with operand
types).

This PR is to solve several intertwined issues with type inference while
adding support for builtins for OpIAddCarry and OpISubBorrow:
* OpIAddCarry and OpISubBorrow generation in a way of supporting SPIR-V
friendly builtins `__spirv_...` -- introduces a new element to account
for, namely, `ptr sret (%struct) %0` argument that is a place to put a
result of the instruction;
* fix early definition of SPIR-V types during call lowering -- namely,
the goal of the PR is to ensure that correct types are applied to
virtual registers which were used as arguments in call lowering and so
caused early definition of SPIR-V types; reproducers are attached as a
new test cases;
* improve parsing of builtin names (e.g., understand a name of a kind
`"anon<int, int> __spirv_IAddCarry<int, int>(int, int)"` that was
incorrectly parsed as `anon` before the PR);
* improve type inference and fix access to erased from parent after
visit instructions -- before the PR visiting of instructions in
emitintrinsics pass replaced old alloca's, bitcast's, etc. instructions
with a newly generated internal SPIR-V intrinsics and after erasing old
instructions there were still references to them in a postprocessing
working list, while records for newly deduced pointee types were lost;
this PR fixes the issue by adding as consistent wrt. internal data
structures action `SPIRVEmitIntrinsics::replaceAllUsesWith()` that fixes
above mentioned problems;
* LLVM IR add/sub instructions result in logical SPIR-V instructions
when applied to bool type;
* fix validation of pointer types for frexp and lgamma_r,
* fix hardcoded reference to AS0 as a Function storage class in
lib/Target/SPIRV/SPIRVBuiltins.cpp -- now it's
`storageClassToAddressSpace(SPIRV::StorageClass::Function)`,
* re-use the same OpTypeStruct for two identical references to struct's
in arithmetic with overflow instructions.

This PR improves implementation of SPV_INTEL_function_pointers and type
inference for phi-nodes and indirect calls.

There are llvm intrinsics which we do not expect to actually represent
code after lowering or which are not implemented yet but can be found in
a customer's LLVM IR input. We do not want translation to crash when
these llvm intrinsics are found, and this PR fixes the issue with
translation crash for some known cases, aligned with Khronos Translator.