Always send log(9) messages to the message buffer.

It is truer to the semantics of logging for messages to *always*
go to the message buffer, where they can eventually be collected
and, in fact, be put into a log file.

This restores the behavior prior to r70239, which seems to have
changed it inadvertently.

Submitted by: Eric Badger <eric@badgerio.us>
Reviewed by: jhb
Approved by: kib (mentor)
Obtained from: Dell Inc.
MFC after: 1 week