Intrinsics implemented with Clang builtins could already be implemented as
either inline functions or macros, but intrinsics implemented directly
(without builtins) could only be inline functions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120763 91177308-0d34-0410-b5e6-96231b3b80d8