[clang] [X86] Finally handle target of __builtin_ia32_cmp[p|s][s|d] from avx into sse/sse2/avx (PR #84136)

[Simon Pilgrim via cfe-commits]

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

LGTM - but @pogo59 needs a headup as it will affect some ongoing documentation cleanup work

https://github.com/llvm/llvm-project/pull/84136