upstream: fix test for executability of tmux

OpenBSD-Regress-ID: a18119876ecfd95edb78225b086ac668eb0977ab

Author: djmdjm

regress/ssh-tty.sh

@@ -1,4 +1,4 @@
-#	$OpenBSD: ssh-tty.sh,v 1.2 2025/10/21 08:34:52 djm Exp $
+#	$OpenBSD: ssh-tty.sh,v 1.3 2025/10/21 08:35:22 djm Exp $
 #	Placed in the Public Domain.
 
 # Basic TTY smoke test
@@ -12,7 +12,7 @@ mkdir -m 0700 -p "$FAKEHOME"
 
 # tmux stuff
 TMUX=${TMUX:-tmux}
-test -x $TMUX || skip "tmux not found"
+type $TMUX >/dev/null || skip "tmux not found"
 CLEANENV="env -i HOME=$HOME LOGNAME=$USER USER=$USER PATH=$PATH SHELL=$SHELL"
 TMUX_TEST="$CLEANENV $TMUX -f/dev/null -Lopenssh-regress-ssh-tty"
 sess="regress-ssh-tty$$"