Handle more edge cases in intrinsic name binary search

I tried to make the AMDGPU intrinsic info table use this instead of
another StringMatcher, and some issues arose.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258871 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed