update pexp in rc.d/sshd to match the new setproctitle ('sshd: [listener]

1 of 10-100 startups').  "makes sense" deraadt@
Beware if you have multiple sshd processes (e.g. on different ports) and
want to restart/stop just one - with the current proctitle there's no way
to distinguish between these so rc.d/rcctl will match all of them.

src/etc/rc.d/sshd

@@ -1,11 +1,13 @@
 #!/bin/ksh
 #
-# $OpenBSD: sshd,v 1.4 2018/01/11 19:52:12 rpe Exp $
+# $OpenBSD: sshd,v 1.5 2020/01/22 13:14:51 sthen Exp $
 
 daemon="/usr/sbin/sshd"
 
 . /etc/rc.d/rc.subr
 
+pexp="sshd: \[listener\].*"
+
 rc_reload() {
 	${daemon} ${daemon_flags} -t && pkill -HUP -xf "${pexp}"
 }