ARM: Prefetch intrinsics

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@215568 91177308-0d34-0410-b5e6-96231b3b80d8
AArch64: Prefetch intrinsic

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@215569 91177308-0d34-0410-b5e6-96231b3b80d8