Some compilers either only compile to an objc v1 or don't compile it at all, while it most likely wouldn't cause issues I added this just in case we stay on objc

Signed-off-by: Exverge <exverge@exverge.xyz>

initial metal backend

revert Upload files to "/"

It is very hard to explain why this public interface class was defined
in an anonymous namespace inside a header file.