remove unnecessary GTK declarations from defs.h, move things only used once to the place that needs them

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69020 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/window.cpp

@@ -2474,7 +2474,7 @@ void wxWindowGTK::PostCreation()
         gtk_widget_show( m_widget );
 }
 
-gulong wxWindowGTK::GTKConnectWidget(const char *signal, void (*callback)())
+unsigned long wxWindowGTK::GTKConnectWidget(const char *signal, void (*callback)())
 {
     return g_signal_connect(m_widget, signal, callback, this);
 }