R600: Add aliases for hainan and mullins

git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@216126 91177308-0d34-0410-b5e6-96231b3b80d8
Implement prefetch builtin

The default implementation is a no-op.  Targets should override this
with their own implementations.

git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@216127 91177308-0d34-0410-b5e6-96231b3b80d8
Add missing file from r216127

git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@216128 91177308-0d34-0410-b5e6-96231b3b80d8