Fix off by one in nested attribute management.

Fixes segv in:
  tc qdisc show dev eth1
due to uninitialized attribute table.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 12883fe..d13596f 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -632,6 +632,6 @@
 		rta = RTA_DATA(rta) + RTA_ALIGN(len);
 		return parse_rtattr_nested(tb, max, rta);
 	}
-	memset(tb, 0, sizeof(struct rtattr *) * max);
+	memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
 	return 0;
 }