MINOR: stream-int: relax the forwarding rules in stream_int_notify()

There currently is an optimization in stream_int_notify() consisting
in not trying to forward small bits of data if extra data remain to be
processed. The purpose is to avoid forwarding one chunk at a time if
multiple chunks are available to be parsed at once. It consists in
avoiding sending pending output data if there are still data to be
parsed in the channel's buffer, since process_stream() will have the
opportunity to deal with them all at once.

Not only this optimization is less useful with the new way the connections
work, but it even causes problems like lost events since WAIT_ROOM will
not be removed. And with HTX, it will never be able to update the input
buffer after the first read.

Let's relax the rules now, by always sending if we don't have the
CF_EXPECT_MORE flag (used to group writes), or if the buffer is
already full.

src/stream_interface.c

@@ -498,7 +498,7 @@ void stream_int_notify(struct stream_interface *si)
 	 */
 	if (!channel_is_empty(ic) &&
 	    (si_opposite(si)->flags & SI_FL_WAIT_DATA) &&
-	    (ci_data(ic) == 0 || ic->pipe)) {
+	    (!(ic->flags & CF_EXPECT_MORE) || c_full(ic) || ci_data(ic) == 0 || ic->pipe)) {
 		int new_len, last_len;
 
 		last_len = co_data(ic);