rib: put PrefixAnnouncement in Route and RibEntry

refs #4650

Change-Id: I03a846cd6e013d52f080bd7b092cd392b0284f88
diff --git a/rib/rib.cpp b/rib/rib.cpp
index 542a582..5385cf1 100644
--- a/rib/rib.cpp
+++ b/rib/rib.cpp
@@ -113,12 +113,10 @@
         scheduler::cancel(entryIt->getExpirationEvent());
       }
 
+      *entryIt = route;
+
       // No checks are required here as the iterator needs to be updated in all cases.
       entryIt->setExpirationEvent(route.getExpirationEvent());
-
-      entryIt->flags = route.flags;
-      entryIt->cost = route.cost;
-      entryIt->expires = route.expires;
     }
   }
   else {