Change the return type of `LLVMIntrinsicCopyOverloadedName` and
`LLVMIntrinsicCopyOverloadedName2` to `char *` instead of `const char *`
since the returned memory is owned by the caller and we expect that the
returned pointer is passed to free to deallocate it (without casting it
back to non-const pointer).
b5dc7b8fc2