CodeGen: add support for a few MSVC ARM intrinsics

This adds support for simple MSVC compatibility mode intrinsics.  These
intrinsics are simple in that they are either directly passed through to the
annotated MSBuiltin intrinsic or they mirror existing GCC builtins.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@212378 91177308-0d34-0410-b5e6-96231b3b80d8