Merge: Objective-C FFI with basic wrapper for the Cocoa, AppKit and Foundation kits...

Merge: Objective-C FFI with basic wrapper for the Cocoa, AppKit and Foundation kits/frameworks

Notes:
* Tweaks to `tests.sh` enables testing some programs on OS X only.
* This is the foundation for more PRs.
* Most cocoa tests are UNDEFINED because they use log. I'll add more tests with simple strings in the future.
* More tests for the FFI are needed.

Pull-Request: #986
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>