DolphinQt: Expose "DisableScreenSaver" setting in the UI.

Source/Core/DolphinQt/Settings/InterfacePane.h

@@ -37,6 +37,7 @@ private:
   QCheckBox* m_checkbox_show_debugging_ui;
   QCheckBox* m_checkbox_focused_hotkeys;
   QCheckBox* m_checkbox_use_covers;
+  QCheckBox* m_checkbox_disable_screensaver;
 
   QCheckBox* m_checkbox_confirm_on_stop;
   QCheckBox* m_checkbox_use_panic_handlers;