Fixed SDL applications being killed immediately after being backgrounded, because they were trying to draw while minimized.

src/render/SDL_sysrender.h

@@ -99,6 +99,7 @@ struct SDL_Renderer
 
     /* The window associated with the renderer */
     SDL_Window *window;
+    SDL_bool minimized;
 
     /* The drawable area within the window */
     SDL_Rect viewport;