make it easier to find leaks by dropping globals at exit

vcl/inc/unx/gtk/gtkdata.hxx

@@ -113,6 +113,7 @@ public:
     virtual ~GtkData();
 
     virtual void Init();
+    virtual void Dispose();
 
     virtual void initNWF();
     virtual void deInitNWF();

vcl/unx/gtk/app/gtkdata.cxx

@@ -550,6 +550,11 @@ GtkData::~GtkData()
     osl_destroyMutex( m_aDispatchMutex );
 }
 
+void GtkData::Dispose()
+{
+    deInitNWF();
+}
+
 void GtkData::Yield( bool bWait, bool bHandleAllCurrentEvents )
 {
     /* #i33212# only enter g_main_context_iteration in one thread at any one

vcl/unx/gtk/gdi/salnativewidgets-gtk.cxx

@@ -467,7 +467,6 @@ void GtkData::initNWF( void )
  *********************************************************/
 void GtkData::deInitNWF( void )
 {
-
     for( unsigned int i = 0; i < gWidgetData.size(); i++ )
     {
         // free up global widgets