[clang] [clang][SPIR-V] Add x86 calling conventions and sse/sse2 for MSVC hosts (PR #227665)

[Tony Guillot via cfe-commits]

https://github.com/to268 commented:

I cannot effectively review this PR for the technical parts related to MSVC and SPIR-V and have privately forwarded this PR to make sure the correct people are assigned.

https://github.com/llvm/llvm-project/pull/227665