ospf6d: Route locking (memory) cleanup

* ospf6_route.c: (ospf6_route_best_next) Allows unlock route, even
  when there's no next route.  This is consistent with how
  ospf6_route_next() behaves.

* ospf6_intra.c: (ospf6_intra_prefix_lsa_remove) Make sure the last
  route considered is always unlocked.  This is needed when the for
  loop terminates because ospf6_route_is_prefix() returns zero.

ospf6d/ospf6_intra.c

@@ -1177,6 +1177,8 @@ ospf6_intra_prefix_lsa_remove (struct ospf6_lsa *lsa)
             }
           ospf6_route_remove (route, oa->route_table);
         }
+      if (route)
+	ospf6_route_unlock (route);
     }
 
   if (current != end && IS_OSPF6_DEBUG_EXAMIN (INTRA_PREFIX))

ospf6d/ospf6_route.c

@@ -690,6 +690,8 @@ ospf6_route_best_next (struct ospf6_route *route)
   struct route_node *rnode;
   struct ospf6_route *next;
 
+  ospf6_route_unlock (route);
+
   rnode = route->rnode;
   route_lock_node (rnode);
   rnode = route_next (rnode);
@@ -701,7 +703,6 @@ ospf6_route_best_next (struct ospf6_route *route)
 
   assert (rnode->info);
   next = (struct ospf6_route *) rnode->info;
-  ospf6_route_unlock (route);
   ospf6_route_lock (next);
   return next;
 }