macos: avoid size/origin changes when possible

macos: avoid size/origin changes when possible

If _gdk_macos_surface_move_resize() was called with various -1 parameters
we really want to avoid changing anything even if we think we know what
the value might be. Otherwise, we risk messing up in-flight operations that
we have not yet been notified of yet.

This improves the chances we place windows in an appropriate location as
they don't et screwed up before window-manager placement.