Fix: Compile warnings when asserts are disabled

src/window.cpp

@@ -1386,6 +1386,7 @@ static void AddWindowToZOrdering(Window *w)
 		/* Search down the z-ordering for its location. */
 		Window *v = _z_front_window;
 		uint last_z_priority = UINT_MAX;
+		(void)last_z_priority; // Unused without asserts
 		while (v != nullptr && (v->window_class == WC_INVALID || GetWindowZPriority(v->window_class) > GetWindowZPriority(w->window_class))) {
 			if (v->window_class != WC_INVALID) {
 				/* Sanity check z-ordering, while we're at it. */