gtk: fix many callback annotations to include closure information

Without this information introspection-based consumers don't realize
they can include context information, but instead think that they
receive an extra gpointer argument (which they don't know how to
handle).

https://bugzilla.gnome.org/show_bug.cgi?id=730745

gtk/deprecated/gtkstock.h

@@ -38,7 +38,8 @@ G_BEGIN_DECLS
  * GtkTranslateFunc:
  * @path: The id of the message. In #GtkActionGroup this will be a label
  *   or tooltip from a #GtkActionEntry.
- * @func_data: user data passed in when registering the function
+ * @func_data: (closure): user data passed in when registering the
+ *   function
  *
  * The function used to translate messages in e.g. #GtkIconFactory
  * and #GtkActionGroup.