*: Widen width of Zserv routing tag field.

* lib/zebra.h: Introduce a route_tag_t type for route tags generally,
  and make it 4 bytes wide - so it can directly hold things like an ASN, or
  the OSPF ASE-LSA tag.
* zebra/rib.h: Use route_tag_t instead of u_short.
* *: Update 'u_short (*)?(tag|tmp)' to use route_tag_t instead of u_short.
  Update stream_{get,put} to l instead of w.
* ospf_zebra.c: (ospf_zebra_add) test OSPF tag within range of ROUTE_TAG_MAX.
diff --git a/ospfd/ospf_lsa.c b/ospfd/ospf_lsa.c
index 4341cd9..d795439 100644
--- a/ospfd/ospf_lsa.c
+++ b/ospfd/ospf_lsa.c
@@ -1649,7 +1649,7 @@
   /* Put forwarding address. */
   stream_put_ipv4 (s, fwd_addr.s_addr);
   
-  /* Put route tag -- only first 16bits are used for compatibility */
+  /* Put route tag */
   stream_putl (s, ei->tag);
 }