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

[Paul T Robinson via cfe-commits]

https://github.com/pogo59 commented:

Thanks for the heads-up @RKSimon I've made suggestions for consistency with existing practice in emmintrin.h which I've adopted in the latest revision to #83316.

I'm unsure how replacing a function declaration with an \fn directive will play with our documentation tooling. But we can figure that out later.

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