Original commit message from CVS:
* ext/sdl/sdlvideosink.c: (gst_sdlvideosink_base_init),
(gst_sdlvideosink_class_init),
(gst_sdlvideosink_get_sdl_from_fourcc), (gst_sdlvideosink_setcaps),
(gst_sdlvideosink_show_frame):
* ext/sdl/sdlvideosink.h:
Fix I420 output on some machines (not very nice, but should work).
Add an 'sdlvideosink' debug category. Disable formats that do
not work. Fix some vararg function issues.