bus: Add a handle_vips() hook invoked after handling configuration attributes

Similar to assign_vips() used by a peer assigning virtual IPs to the other peer,
the handle_vips() hook gets invoked on a peers after receiving attributes. On
release of the same attributes the hook gets invoked again.

This is useful to inspect handled attributes, as the ike_updown() hook is
invoked after authentication, when attributes have not been handled yet.

src/libcharon/sa/ike_sa.c

@@ -2168,6 +2168,7 @@ METHOD(ike_sa_t, destroy, void,
 	}
 
 	/* remove attributes first, as we pass the IKE_SA to the handler */
+	charon->bus->handle_vips(charon->bus, &this->public, FALSE);
 	while (array_remove(this->attributes, ARRAY_TAIL, &entry))
 	{
 		if (entry.handler)