Try again to revert the bad patch. The tree was reverted for some unknown reason
before the last time.

--- Reverse-merging r171442 into '.':
U    include/llvm/IR/Attributes.h
U    lib/IR/Attributes.cpp
U    lib/IR/AttributeImpl.h



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171448 91177308-0d34-0410-b5e6-96231b3b80d8