status: suppress status_trace/status_debug messages if queue too long.

We can be spammy, which is good for tests, but bad for our simple message queue.
This avoids breaking our tests but also avoid the worst case (1M entries and counting!)
for gossip status messages in the case where we're syncing a large peer.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

common/msg_queue.c

@@ -22,6 +22,11 @@ static void do_enqueue(struct msg_queue *q, const u8 *add TAKES)
 	io_wake(q);
 }
 
+size_t msg_queue_length(const struct msg_queue *q)
+{
+	return tal_count(q->q);
+}
+
 void msg_enqueue(struct msg_queue *q, const u8 *add)
 {
 	assert(fromwire_peektype(add) != MSG_PASS_FD);