[CostModel][X86] Add some initial cost tests for funnel shifts

Still need to add full uniform/constant coverage but this is enough to check basic fshl/fshr cost handling

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346670 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed