[X86][XOP] Add codegen tests for vector integer comparison intrinsics (PR15844)

We were testing for the generic _mm_com_* intrinsics, but not the specific comparison mode versions.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@297885 91177308-0d34-0410-b5e6-96231b3b80d8