[NET]: Transform skb_queue_len() binary tests into skb_queue_empty()

This is part of the grand scheme to eliminate the qlen
member of skb_queue_head, and subsequently remove the
'list' member of sk_buff.

Most users of skb_queue_len() want to know if the queue is
empty or not, and that's trivially done with skb_queue_empty()
which doesn't use the skb_queue_head->qlen member and instead
uses the queue list emptyness as the test.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index c420eba..d403e34 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -302,7 +302,7 @@
  * may receive messages only from that peer. */
 static void unix_dgram_disconnected(struct sock *sk, struct sock *other)
 {
-	if (skb_queue_len(&sk->sk_receive_queue)) {
+	if (!skb_queue_empty(&sk->sk_receive_queue)) {
 		skb_queue_purge(&sk->sk_receive_queue);
 		wake_up_interruptible_all(&unix_sk(sk)->peer_wait);
 
@@ -1619,7 +1619,7 @@
 	for (;;) {
 		prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
 
-		if (skb_queue_len(&sk->sk_receive_queue) ||
+		if (!skb_queue_empty(&sk->sk_receive_queue) ||
 		    sk->sk_err ||
 		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
 		    signal_pending(current) ||