[clang] [Clang][X86] Add tests for AVX512 integer comparison intrinsics to be used in constexpr (PR #169452)

[via cfe-commits]

shri-acha wrote:

I checked out the changes made by me and it seems as though, I was confused, so as to not to be confused in making any future changes, I'd like to explain my understand and please mention if I am wrong in anyway:

> When we mention ep(i/u)8 , I will be using explicitly signed vectors like _v64q(s/u)
> When we mention ep(i/u)16, I will be using _v32h(i/u)
> When we mention ep(i/u)32, I will be using _v32s(i/u)
> When we mention ep(i/u)64, I will be using _v32d(i/u)


https://github.com/llvm/llvm-project/pull/169452