* clutter/Makefile.am:
	* clutter/clutter-enum-types.h.in:
	* clutter/clutter-enum-types.c.in: Use template files for
	glib-mkenums; this makes the Makefile template a bit more
	clean and the enum types generation more customisable (e.g.
	when GLib 2.14 has been released, we can use g_once_init_enter()
	and g_once_init_leave() to have thread-safe GType functions
	for the enum types as well).