Add missing add_blacklist for OpenGl apps

src/gl/imgui_hud.cpp

@@ -67,8 +67,15 @@ void imgui_init()
 {
     if (cfg_inited)
         return;
-    is_blacklisted(true);
+
     parse_overlay_config(&params, getenv("MANGOHUD_CONFIG"));
+
+   //check for blacklist item in the config file
+   for (auto& item : params.blacklist) {
+      add_blacklist(item);
+   }
+
+    is_blacklisted(true);
     notifier.params = &params;
     start_notifier(notifier);
     window_size = ImVec2(params.width, params.height);