Core: Implement automatic symbol demangling

Source/Core/DolphinQt/MenuBar.h

@@ -310,6 +310,7 @@ private:
   QAction* m_jit_systemregisters_off;
   QAction* m_jit_branch_off;
   QAction* m_jit_register_cache_off;
+  QAction* m_debugger_show_demangled_names;
 
   bool m_game_selected = false;