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

[Simon Pilgrim via cfe-commits]

RKSimon wrote:

> I'm not sure if the __v4q* type exists or not, I saw one commit in gcc's history, so I assumed it exists. also, I'll get the remaining tests for __mm512 and _mm*_mask_cmp*_ep**_mask.

These are defined in avx512vlintrin.h to help with truncations:
```
typedef short __v2hi __attribute__((__vector_size__(4)));
typedef char __v4qi __attribute__((__vector_size__(4)));
typedef char __v2qi __attribute__((__vector_size__(2)));
```

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