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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

lib: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified 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.

Move my simple logging API to a separate library. It is now already used
by hastctl(8), hastd(8) and auditdistd(8) and will soon be also used
by casperd(8) and its services. There is no documentation and pjdlog.h
header file is not installed in /usr/include/ to keep it private.
Unfortunately we don't have /lib/private/ at this point, only
/usr/lib/private/, so the library is installed in /lib/.

Sponsored by: The FreeBSD Foundation