Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

/*- or .\"- or #- to begin license clauses.

$Id$ -> $FreeBSD$

This commit was generated by cvs2svn to compensate for changes in r23449,
which included commits to RCS files with non-trunk default branches.

Import Jason Thorpe's contribution for an updated SCSI media changer
device (now, finally!).