Restore the order in which RFC 3164 messages with fac/pri are formatted.

The refactoring of the syslogd code to format messages using iovecs
slightly altered the output of syslogd by placing the facility/priority
after the hostname, as opposed to printing it right before. This change
reverts the behaviour to be consistent with how it was before.

PR: 229457
Reported by: Andre Albsmeier
MFC after: 1 week