[LLVM-C] Add Builder Bindings to Common Memory Intrinsics

Summary: Add IRBuilder bindings for memmove, memcpy, and memset.

Reviewers: whitequark, deadalnix

Reviewed By: whitequark

Subscribers: harlanhaskins, llvm-commits

Differential Revision: https://reviews.llvm.org/D53555

llvm-svn: 345508