Update backdrop.c

src/backdrop.c

@@ -1,8 +1,7 @@
 #include <SDL2/SDL.h>
 #include <stdbool.h>
-
-extern SDL_Renderer *sr;
-extern bool gradient_d;
+#include "sdl.h"
+#include "events.h"
 
 enum gradient {Blue = 0, Green = 10, Red = 20, Yellow = 30, Magenta = 40, Cyan = 50, Grey = 60} colour = 0;