update_relation

Updates a list of accessible relations.

This function should be called by `GtkWidget` types whenever an accessible relation change must be communicated to assistive technologies.

If the [enum@Gtk.AccessibleRelation] requires a list of references, you should pass each reference individually, followed by null, e.g.

```c gtk_accessible_update_relation (accessible, GTK_ACCESSIBLE_RELATION_CONTROLS, ref1, NULL, GTK_ACCESSIBLE_RELATION_LABELLED_BY, ref1, ref2, ref3, NULL, -1); ```

Parameters:

this	a `GtkAccessible`
...	a list of relation and value pairs, terminated by -1
first_relation	the first `GtkAccessibleRelation`