- Make route cacheing optional, configurable via IFF_LINK0 flag.

- Turn it off by default.

Requested by:	many
Reviewed by:	andre
Approved by:	julian (mentor)
MFC after:	3 days

sys/netinet/in_gif.c

@@ -209,6 +209,12 @@ in_gif_output(ifp, family, m)
 	}
 
 	error = ip_output(m, NULL, &sc->gif_ro, 0, NULL, NULL);
+
+	if ((sc->gif_if.if_flags & IFF_LINK0) == 0) {
+		RTFREE(sc->gif_ro.ro_rt);
+		sc->gif_ro.ro_rt = NULL;
+	}
+
 	return (error);
 }