*: 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_asbr.h b/ospfd/ospf_asbr.h
index 2709a6c..bc41a14 100644
--- a/ospfd/ospf_asbr.h
+++ b/ospfd/ospf_asbr.h
@@ -63,7 +63,7 @@
                                               struct prefix_ipv4,
 					      ifindex_t, 
 					      struct in_addr,
-					      u_short);
+					      route_tag_t);
 extern void ospf_external_info_delete (u_char, struct prefix_ipv4);
 extern struct external_info *ospf_external_info_lookup (u_char, 
                                                  struct prefix_ipv4 *);