Exit exclusive fullscreen when the stop confirmation is shown.

Also have the renderer remember its own fullscreen state. This is done to prevent a case where we exit exclusive fullscreen through the configuration and a focus shift at the same time. In this case the renderer would fail to detect that the fullscreen state was changed.

Source/Core/DolphinWX/Frame.h

@@ -170,6 +170,7 @@ private:
 	bool m_bNoDocking;
 	bool m_bGameLoading;
 	bool m_bClosing;
+	bool m_confirmStop;
 
 	std::vector<std::string> drives;