Fix build with gtk2 older than 2.20 by using the old definition

Change-Id: I3355d25f04a3c57063fd3d03e72a75da32e16efc
Reviewed-on: https://gerrit.libreoffice.org/21109Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>

vcl/unx/gtk/gtksalframe.cxx

@@ -83,8 +83,8 @@
 
 #include <config_folders.h>
 
-#define IS_WIDGET_REALIZED gtk_widget_get_realized
-#define IS_WIDGET_MAPPED   gtk_widget_get_mapped
+#define IS_WIDGET_REALIZED GTK_WIDGET_REALIZED
+#define IS_WIDGET_MAPPED   GTK_WIDGET_MAPPED
 
 using namespace com::sun::star;