[X86] Add a few more fptosi test cases to demonstrate -x86-experimental-vector-widening legalization not combining vpacksswb+vpmovdw.

We are able to combine vpackuswb+vpmovdw, but we didn't have packsswb+vpmovdw at the time that combine was added.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@348909 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed