Fixed bug 3742 - minor warning fixes

src/video/x11/SDL_x11video.c

@@ -26,6 +26,7 @@
 
 #include "SDL_video.h"
 #include "SDL_mouse.h"
+#include "SDL_timer.h"
 #include "../SDL_sysvideo.h"
 #include "../SDL_pixels_c.h"