Add back support for null0 interface blackhole routes.
diff --git a/lib/zebra.h b/lib/zebra.h
index baad6d6..7b1e801 100644
--- a/lib/zebra.h
+++ b/lib/zebra.h
@@ -271,6 +271,7 @@
 #define ZEBRA_NEXTHOP_IPV6               6
 #define ZEBRA_NEXTHOP_IPV6_IFINDEX       7
 #define ZEBRA_NEXTHOP_IPV6_IFNAME        8
+#define ZEBRA_NEXTHOP_BLACKHOLE          9
 
 #ifndef INADDR_LOOPBACK
 #define	INADDR_LOOPBACK	0x7f000001	/* Internet address 127.0.0.1.  */