[llvm] [llvm-ml] Add MASM unwind v3 support for x64 exception handling and improve MSVC compat (PR #202809)

[Mikołaj Piróg via llvm-commits]

https://github.com/mikolaj-pirog approved this pull request.

LGTM outside of the ReleaseNotes where it seems like unv3-only features are listed for non-unv3 usage


https://github.com/llvm/llvm-project/pull/202809