[x86] add tests to show current codegen for vblendv*; NFC

As noted in the comments, we should be able to eliminate cmp ops
in several cases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@294263 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed