Fix crash when launching game with non-default GUI scale in config

See: #459

src/video/cocoa/cocoa_wnd.mm

@@ -1271,7 +1271,7 @@ void CocoaDialog(const char *title, const char *message, const char *buttonLabel
 /** Screen the window is on changed. */
 - (void)windowDidChangeBackingProperties:(NSNotification *)notification
 {
-	bool did_adjust = AdjustGUIZoom(true);
+	bool did_adjust = AdjustGUIZoom(AGZM_AUTOMATIC);
 
 	/* Reallocate screen buffer if necessary. */
 	driver->AllocateBackingStore();