Implement Cursor Locking and new input focus checks for it

Source/Core/DolphinQt/Settings/InterfacePane.h

@@ -45,4 +45,5 @@ private:
   QCheckBox* m_checkbox_show_active_title;
   QCheckBox* m_checkbox_pause_on_focus_lost;
   QCheckBox* m_checkbox_hide_mouse;
+  QCheckBox* m_checkbox_lock_mouse;
 };