*: Port Christians tweaks for 32-bit route tags

Port over Christian's tweaks from his port of my commit widening the
route-tag field width to 32-bit.  Commit dc9ffce8786844
 "*: Consistently support 32-bit route tags".

with "changes which make this actually useful for all the daemons".

This is missing the zebra route-map changes.
diff --git a/ospfd/ospf_asbr.h b/ospfd/ospf_asbr.h
index bc41a14..0fc3302 100644
--- a/ospfd/ospf_asbr.h
+++ b/ospfd/ospf_asbr.h
@@ -44,7 +44,7 @@
   /* Nexthop address. */
   struct in_addr nexthop;
 
-  /* Additional Route tag. */
+  /* Additional Route tag: this is the wire type */
   u_int32_t tag;
 
   struct route_map_set_values route_map_set;