Implement bzero, memset, memmove builtins.

This subsumes Nico Weber's patch and implements bzero in terms
of llvm.memset to match llvm-gcc.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@53888 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed