Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

Add mrsasutil(8) as alias to mfiutil(8)

mfiutil(8) in theory can work on devices attached to mrsas(4) but
mrsas(4) is missing the FreeBSD mfi(4) ioctl support. Once that
support is added to mrsas(4) then mrsasutil(8) can manage mrsas(4)
attached devices. So this commit depends on that. When mrsasutil(8)
is run it automatically opens /dev/mrsas0 instead of /dev/mfi0.
Add -D <device> and -t <type> flag to optionally specify mrsas or mfi to
work with the existing -u <unit>. Device is the device node with or
without /dev/

PR: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=265794
Differential Revision: https://reviews.freebsd.org/D36343
Tested by: Dan Mahoney <freebsd@gushi.org>
Reviewed by: jhb

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

mfiutil: increase buffer size to accommodate sprintf string

PR: 201289
MFC after: 1 week

Implement foreign volume handling. Allows admins to view foreign metadata
and clear or import it for use.

PR: kern/172091
Submitted by: smh@freebsd.org
Reviewed by: jhb@freebsd.org
MFC after: 2 weeks