zebra: ZEBRA_HELLO and mopping up routes (BZ#448)

ZEBRA_HELLO message is used by routing daemons to inform zebra
what type of routes daemon will be announcing to zebra. Also
zebra uses route_type_oaths array to track which daemon announces
which protocol. Zebra mops up routes if daemon didn't for some
reason.
diff --git a/zebra/rib.h b/zebra/rib.h
index 887ed3c..20a206e 100644
--- a/zebra/rib.h
+++ b/zebra/rib.h
@@ -266,6 +266,7 @@
 extern void rib_sweep_route (void);
 extern void rib_close (void);
 extern void rib_init (void);
+extern unsigned long rib_score_proto (u_char proto);
 
 extern int
 static_add_ipv4 (struct prefix *p, struct in_addr *gate, const char *ifname,