util: Don't use clutter_x11_set_use_argb_visual() on non-X11
util: Don't use clutter_x11_set_use_argb_visual() on non-X11

We shouldn't be running this on non-X11 windowing systems.

https://bugzilla.gnome.org/show_bug.cgi?id=696687

GNOME/clutter-gtk,GNOME/clutter-gtk