Various cleanups

[StephanTLavavej]

These non-overlapping changes are structured as a series of fine-grained commits for easy reviewing but are collected into a single PR to reduce the load on the CI system.

• <xlocinfo>, <xlocnum>: The _Stof and _Stofx families are unused, so we can remove their declarations from stl/inc.
  • xstof.cpp, xstod.cpp, xstold.cpp: We can comment their definitions as preserved for bincompat in stl/src.
  • xwstof.cpp, xwstod.cpp, xwstold.cpp: Also comment the wide definitions, which didn't have declarations.
  • Note that all of these definitions are marked as _CRTIMP2_PURE, so they'll continue to be exported.
• <xlocinfo>: _GetLocaleForCP was declared but never defined, so we can drop this extremely complicated declaration.
• <string>: Qualify _STD getline().
  • This revealed a more subtle problem: the first overload being changed here was calling the second (unintentionally relying on ADL 🙀 because the second hadn't been declared yet), also spending an unnecessary function call. Adding _STD move(_Istr) fixes this, and makes all of these overloads call the actual implementation above.
• special_math.cpp: Now that we've merged update boost-math and fix std::ellint_2 #3077 to always use the standalone boost-math submodule, we can simplify this:
  • We don't need to define BOOST_CHRONO_HEADER_ONLY and BOOST_CONFIG_SUPPRESS_OUTDATED_MESSAGE.
  • We can suppress fewer warnings. We still need to suppress C6326, reported upstream as bessel.hpp and gamma.hpp emit MSVC /analyze warning C6326: Potential comparison of a constant with another constant. boostorg/math#853. We also need to suppress C4702 for the MSVC-internal build's chpe architecture.
• P0896R4_ranges_alg_is_permutation/test.cpp: Nitpick, we conventionally avoid defining a struct and a variable simultaneously. Define NonCopyableBool and b separately.
• Skip a libcxx test due to a possible path length issue.
  • This is consistently failing on my local machine. I suspect this was introduced when Update LLVM #2976 updated LLVM, although I didn't verify that.
• Remove compiler bug workarounds for LLVM-46269 which was fixed in Clang 15.
  • Thanks to @CaseyCarter for providing the desired definition of payload_destructor, also removing an unnecessary semicolon.
• azure-devops/cmake-configure-build.yml: Followup to Update google-benchmark to 1.7.0 #3151, drop unused variables when configuring the benchmarks. This fixes a warning message printed by Azure Pipelines:

CMake Warning:
    Manually-specified variables were not used by the project:

    LIT_FLAGS
    STL_USE_ANALYZE

[CaseyCarter]

For posterity: I validated there are no other occurrences of LLVM-46269 in the STL after applying this change.

[StephanTLavavej]

I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

[StephanTLavavej]

I've pushed an additional commit to restore C4702 silencing for the internal chpe build.