Move to having a single real instructionClobbersQuery

Summary: We really want to move towards MemoryLocOrCall (or fix AA) everywhere, but for now, this lets us have a single instructionClobbersQuery.

Reviewers: george.burgess.iv

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D23072

llvm-svn: 277530