ccan: update to get ccan/io shutdown fix.

Changelog-Fixed: Protocol: fix occasional lost sending of final packet (usually warnings or errors).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/README

@@ -1,3 +1,3 @@
 CCAN imported from http://ccodearchive.net.
 
-CCAN version: init-2595-ge43c61c4
+CCAN version: init-2597-gc4760b30

ccan/ccan/io/io.c

@@ -583,8 +583,10 @@ struct io_plan *io_sock_shutdown(struct io_conn *conn)
 	if (shutdown(io_conn_fd(conn), SHUT_WR) != 0)
 		return io_close(conn);
 
-	/* And leave unset .*/
-	return &conn->plan[IO_IN];
+	/* We need to make sure we don't try to write again, so
+	 * "wait" on something which will never be woken: otherwise
+	 * we will try to write, fail, and immediately close. */
+	return io_wait_dir(conn, io_sock_shutdown, IO_OUT, io_never, NULL);
 }
 
 bool io_flush_sync(struct io_conn *conn)