Fixed Linux build

src/video/x11/SDL_x11xfixes.c

@@ -76,7 +76,7 @@ X11_XfixesIsInitialized()
 void
 X11_SetWindowMouseRect(_THIS, SDL_Window * window)
 {
-    if (SDL_RectEmpty(window->mouse_rect)) {
+    if (SDL_RectEmpty(&window->mouse_rect)) {
         X11_ConfineCursorWithFlags(_this, window, NULL, 0);
     } else {
         if (window->flags & SDL_WINDOW_INPUT_FOCUS) {