[clang] [CLANG-CL] Remove the 'static' specifier for _FUNCTION_ in MSVC mode. (PR #128184)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman approved this pull request.

LGTM with a nit.

Please be sure to add a release note to `clang/docs/ReleaseNotes.rst` for the fix. Also, please add a test for `constexpr` (I believe we handle that correctly, but we might as well make sure we handle all the storage class specifiers at once).

https://github.com/llvm/llvm-project/pull/128184