Make linux compile the loading window code.

NOTE: The actual loading window code is stubbed.
I do not know GTK window code yet, so hopefully
this won't crash yet.

src/arch/LoadingWindow/LoadingWindow_Gtk.h

@@ -11,8 +11,10 @@ public:
 	LoadingWindow_Gtk();
 	RString Init();
 	~LoadingWindow_Gtk();
-
 	void SetText( RString str );
+	void SetProgress( const int progress );
+	void SetTotalWork( const int totalWork );
+	void SetIndeterminate( bool indeterminate );
 };
 #define USE_LOADING_WINDOW_GTK