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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

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.

Improve SRV records support for the pkg(8) bootstrap:
- order srv records by priorities
- for all entries of the same priority, order randomly respect the weight
- select the port where to fetch from respect the port provided in the SRV record

Obtained from: pkg git repo
MFC after: 3 days

if PACKAGESITE url scheme is not 'file://', always try to revolv SRV records and
use them if any. It allows the bootstrap to use directly pkg.FreeBSD.org instead
of pkgbeta.FreeBSD.org

MFC after: 1 month