Static: Fix reset neighbor entries for ECMP routes

Neighbor entries for static ECMP routes were not cleaned up during
reconfigure and pointed to the old instances, which leads to crash
after reconfigure.

Thanks to Vladimir Osmolovskiy for the bugreport.

proto/static/static.c

@@ -518,6 +518,11 @@ static_match(struct proto *p, struct static_route *r, struct static_config *n)
   if (r->neigh)
     r->neigh->data = NULL;
 
+  if (r->dest == RTD_MULTIPATH)
+    for (t = r->mp_next; t; t = t->mp_next)
+      if (t->neigh)
+	t->neigh->data = NULL;
+
   WALK_LIST(t, n->iface_routes)
     if (static_same_net(r, t))
       goto found;