the generated FastISel. X86 doesn't need to generate code to match ADD16ri8
since ADD16ri will do just fine. This is a small codesize win in the generated
instruction selector.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129692 91177308-0d34-0410-b5e6-96231b3b80d8