Revert for now:

--- Reverse-merging r174010 into '.':
U    include/llvm/IR/Attributes.h
U    lib/IR/Verifier.cpp
U    lib/IR/Attributes.cpp



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174012 91177308-0d34-0410-b5e6-96231b3b80d8