upstream: Wait a bit longer for the multiplex master to become ready

since on very slow hosts the current delay is not sufficient and the test
will fail.

OpenBSD-Regress-ID: 6d90c7475d67ac3a95610b64af700629ece51a48

regress/multiplex.sh

@@ -1,4 +1,4 @@
-#	$OpenBSD: multiplex.sh,v 1.30 2019/07/05 04:03:13 dtucker Exp $
+#	$OpenBSD: multiplex.sh,v 1.31 2020/01/25 00:27:56 dtucker Exp $
 #	Placed in the Public Domain.
 
 make_tmpdir
@@ -18,7 +18,7 @@ P=3301  # test port
 
 wait_for_mux_master_ready()
 {
-	for i in 1 2 3 4 5; do
+	for i in 1 2 3 4 5 6 7 8 9; do
 		${SSH} -F $OBJ/ssh_config -S $CTL -Ocheck otherhost \
 		    >/dev/null 2>&1 && return 0
 		sleep $i