* clutter/sdl/clutter-stage-sdl.[ch]: Port the SDL stage to
the new stage implementation API.
* clutter/sdl/clutter-backend-sdl.[ch]: Port the SDL backend
to the new backend API.
* clutter/sdl/clutter-event-sdl.c:
(clutter_event_dispatch): Assign the default stage as the
origin of the event.
* clutter/Makefile.am:
* clutter/clutter-stage.c:
* clutter/sdl/Makefile.am:
* clutter/sdl/clutter-backend-sdl.c:
* clutter/sdl/clutter-backend-sdl.h:
* clutter/sdl/clutter-event-sdl.c:
* clutter/sdl/clutter-sdl.h:
* clutter/sdl/clutter-stage-sdl.c:
* clutter/sdl/clutter-stage-sdl.h:
* configure.ac:
Add a basic SDL based backend. Lacks real input event handling
(translation) as yet.
Also allows for clutter to be built against dgles.
