BUG/MINOR: proto_tcp: Report warning messages when listeners are bound

When a TCP listener is bound, in the tcp_bind_listener() function, a warning
message may be reported and should be displayed on verbose mode. But the warning
message is actually lost if the socket is successfully bound because we don't
fill the <errmsg> variable in this case.

This patch should fix the issue #863. No backport is needed.

src/proto_tcp.c

@@ -677,7 +677,7 @@ int tcp_bind_listener(struct listener *listener, char *errmsg, int errlen)
 
 	/* the socket is ready */
 	listener->state = LI_LISTEN;
-	return err;
+	goto tcp_return;
 
  tcp_close_return:
 	close(fd);