[X86] Add avx512vl command lines to the 128/256-bit vector-lzcnt tests so we can...

[X86] Add avx512vl command lines to the 128/256-bit vector-lzcnt tests so we can see what compare instructions are being used in the lookup table code.

I noticed the 512-bit lzcnts don't use the X86 specific lookup table code and instead use the EXPAND case in LegalizeDAG. I was toying around with fixing this and noticed it would require compare instructions that generate i1 masks and then converting from mask to vector. Then I noticed that we don't test which compares are used with avx512vl and no avx512cd.

llvm-svn: 303020