Ensure that SDL_AddTimer() is never called with a delay of 0 because

this leads to a runaway creation of timers. We never pass 0 currently
but it is safer to check for it explicitly as changes to the code can
easily lead to 0 being used.

Originally committed as revision 14934 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffplay.c

@@ -916,6 +916,7 @@ static Uint32 sdl_refresh_timer_cb(Uint32 interval, void *opaque)
 /* schedule a video refresh in 'delay' ms */
 static void schedule_refresh(VideoState *is, int delay)
 {
+    if(!delay) delay=1; //SDL seems to be buggy when the delay is 0
     SDL_AddTimer(delay, sdl_refresh_timer_cb, is);
 }