ffplay: introduce key repeats

Key repeats have been introduced simply because they improve usability in my
experience for volume, brightness, and other such controls by speeding up the
time taken to go from 0 to max intensity. As a side benefit, this enables rapid
seeking through a file via left/right keys.
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>

ffplay.c

@@ -3740,6 +3740,8 @@ int main(int argc, char **argv)
     SDL_EventState(SDL_SYSWMEVENT, SDL_IGNORE);
     SDL_EventState(SDL_USEREVENT, SDL_IGNORE);
 
+    SDL_EnableKeyRepeat(SDL_DEFAULT_REPEAT_DELAY, SDL_DEFAULT_REPEAT_INTERVAL);
+
     if (av_lockmgr_register(lockmgr)) {
         av_log(NULL, AV_LOG_FATAL, "Could not initialize lock manager!\n");
         do_exit(NULL);