opensmtpd: set a tag in the log runit service.

... otherwise somehow it fallsback to a random system account.

srcpkgs/opensmtpd/files/opensmtpd/log/run

@@ -1,2 +1,2 @@
 #!/bin/sh
-exec logger -p mail.notice
+exec logger -p mail.notice -t opensmtpd

srcpkgs/opensmtpd/template

@@ -1,7 +1,7 @@
 # Template file for 'opensmtpd'
 pkgname=opensmtpd
 version=5.4.4p1
-revision=3
+revision=4
 build_style=gnu-configure
 configure_args="--sysconfdir=/etc/smtpd --sbindir=/usr/sbin
  --with-maildir=/var/spool/mail --with-privsep-path=/var/db