* (QB) Add rule for Metal - define HAVE_COCOA_METAL for now
when building for Metal, and HAVE_COCOA for non-Metal build
* Make necessary changes to Makefile.common and qb/config.libs.sh:
- Disable OpenGL for now for Metal build
- Take Metal conditional out of OpenGL block in Makefile.common
* (Metal) Header fixes for compiling without Xcode/Griffin
* (Mac) Some buildfixes for non-Xcode building
* (cocoa_common.h) Restructure to no longer use -DOSX
* (Apple) More buildfixes
* (Apple) Cleanups
* OSD message background
* clear glui background
* add Metal to configuration
* added optional config to compile Metal build without OpenGL
* fixed fill_pathname_join_delim; if out_path and dir are same, don't
strlcpy, as the results are undefined.