[IRBuilder] Add APIs for creating calls to atomic memmove and memset intrinsics. (NFC)

Summary:
Creating the IRBuilder methods:
 CreateElementUnorderedAtomicMemSet
 CreateElementUnorderedAtomicMemMove

These mirror the methods that create calls to the regular (non-atomic) memmove and
memset intrinsics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333588 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed