[InstCombine] add tests for funnel shifts; NFC

These are included in D54666, so adding them first with baseline results.

Patch by: @nikic (Nikita Popov)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347333 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed