this new SDL_USE240P flag must be provided to SDL_SetVideoMode if
the application wants to use a 240p TV video mode _AND_ only is used
if the video mode being set with SDL_SetVideoMode is 320x240. otherwise
libogc's VIDEO_GetPreferredMode is used which will result in either
480i or 480p
also borrowed some of the logic from VIDEO_GetPreferredMode to set an
equivalent video mode to 240p for PAL regions
Gered
