Reinit panel on vsync toggle.

Destroy the DrawingPanel on vsync checkbox toggle so that it is
re-created with the vsync option in effect.

Signed-off-by: Rafael Kitover <rkitover@gmail.com>

src/wx/cmdevents.cpp

@@ -3210,6 +3210,11 @@ EVT_HANDLER(VSync, "Wait for vertical sync")
 {
     GetMenuOptionInt("VSync", &vsync, 1);
     update_opts();
+
+    if (panel->panel) {
+        panel->panel->Destroy();
+        panel->panel = nullptr;
+    }
 }
 
 void MainFrame::EnableNetworkMenu()