zebra: Add missing debug guard in rt netlink code

Guard a debug in the rt netlink code.

Signed-off-by: Carmine Scarpitta <[email protected]>
(cherry picked from commit d9e8c1e)

Author: cscarpitta

zebra/rt_netlink.c

@@ -1498,8 +1498,9 @@ int netlink_route_change(struct nlmsghdr *h, ns_id_t ns_id, int startup)
 
 	if (!(h->nlmsg_type == RTM_NEWROUTE || h->nlmsg_type == RTM_DELROUTE)) {
 		/* If this is not route add/delete message print warning. */
-		zlog_debug("Kernel message: %s NS %u",
-			   nl_msg_type_to_str(h->nlmsg_type), ns_id);
+		if (IS_ZEBRA_DEBUG_KERNEL)
+			zlog_debug("Kernel message: %s NS %u", nl_msg_type_to_str(h->nlmsg_type),
+				   ns_id);
 		return 0;
 	}