[clang] [Headers][X86] Enable constexpr handling for MMX/SSE/AVX/AVX512 PMADDWD/PMADDUBSW intrinsics (PR #161563)

[Bhasawut Singhaphan via cfe-commits]

markbhasawut wrote:

@RKSimon I tried to get this PR a label, but the automate-prs-labels didn't run even I triggered it by updating the branch. Do you have any suggestions?

https://github.com/llvm/llvm-project/pull/161563