*: 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/zebra/zebra_vty.c b/zebra/zebra_vty.c
index a14f68b..38f61e9 100644
--- a/zebra/zebra_vty.c
+++ b/zebra/zebra_vty.c
@@ -54,7 +54,7 @@
   struct in_addr mask;
   const char *ifname;
   u_char flag = 0;
-  u_short tag = 0;
+  route_tag_t tag = 0;
   vrf_id_t vrf_id = VRF_DEFAULT;
   
   ret = str2prefix (dest_str, &p);
@@ -2451,7 +2451,7 @@
   struct route_node *rn;
   struct rib *rib;
   int first = 1;
-  u_short tag = 0;
+  route_tag_t tag = 0;
   vrf_id_t vrf_id = VRF_DEFAULT;
 
   if (argv[0])
@@ -3386,7 +3386,7 @@
   u_char type = 0;
   vrf_id_t vrf_id = VRF_DEFAULT;
   u_char flag = 0;
-  u_short tag = 0;
+  route_tag_t tag = 0;
   
   ret = str2prefix (dest_str, &p);
   if (ret <= 0)
@@ -4496,7 +4496,7 @@
   struct route_node *rn;
   struct rib *rib;
   int first = 1;
-  u_short tag = 0;
+  route_tag_t tag = 0;
   vrf_id_t vrf_id = VRF_DEFAULT;
 
   if (argv[0])