[SelectionDAG] Add a isel matcher op to check the type of node results other than result 0.

I plan to use this to check the type of the mask result of masked gathers in the X86 backend.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318820 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed