quartz: honor more source image properties in _gdk_quartz_image_copy_to_image()
quartz: honor more source image properties in _gdk_quartz_image_copy_to_image()

Particularly look at the source image's byte order when making a
screenshot of the "root window" (which is the window stack). Make
the code more generic so it can handle all sorts of pixel formats.

Distrotech/gtk,johne53/MB3Gtk-2,Distrotech/gtk,johne53/MB3Gtk-2,Distrotech/gtk,johne53/MB3Gtk-2,johne53/MB3Gtk-2,Distrotech/gtk,Distrotech/gtk,johne53/MB3Gtk-2