Don't directly include GTK+ semi-public headers.

Only the main headers (e.g. gtk/gtk.h) should be included and GTK+ 3 is strict about this. Enable compile-time checks for this that work with GTK+ 2.24.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67137 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/print.cpp

@@ -36,7 +36,7 @@
 #include "wx/paper.h"
 
 #include <gtk/gtk.h>
-#include <gtk/gtkpagesetupunixdialog.h>
+#include <gtk/gtkunixprint.h>
 
 #if wxUSE_GRAPHICS_CONTEXT
 #include "wx/graphics.h"