ospf6d: add SNMP notifications/traps support

Only implement ospfv3NbrStateChange and ospfv3IfStateChange.
diff --git a/ospf6d/ospf6_interface.c b/ospf6d/ospf6_interface.c
index 6f7aaa8..40cda24 100644
--- a/ospf6d/ospf6_interface.c
+++ b/ospf6d/ospf6_interface.c
@@ -421,6 +421,17 @@
       OSPF6_INTRA_PREFIX_LSA_SCHEDULE_TRANSIT (oi);
       OSPF6_INTRA_PREFIX_LSA_SCHEDULE_STUB (oi->area);
     }
+
+#ifdef HAVE_SNMP
+  /* Terminal state or regression */ 
+  if ((next_state == OSPF6_INTERFACE_POINTTOPOINT) ||
+      (next_state == OSPF6_INTERFACE_DROTHER) ||
+      (next_state == OSPF6_INTERFACE_BDR) ||
+      (next_state == OSPF6_INTERFACE_DR) ||
+      (next_state < prev_state))
+    ospf6TrapIfStateChange (oi);
+#endif
+
 }