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

Similar commit in main:
(cherry picked from commit b3e7694832e8)

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

(cherry picked from commit 4d846d260e2b9a3d4d0a701462568268cbfe7a5b)

This allows preferring small (e.g. ACK) packets, in upload heavy
environments.

It was already possible to mark packets urgent based on destination
port. This option piggy backs on that feature.

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.

getenv(3) returns NULL if the variable name is not in the current
environment.
getservent(3) returns NULL on EOF or error

MFC after:	4 weeks

usr.sbin/ppp/command.c:2054:74: error: address of array 'arg->bundle->radius.cfg.file'
will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
      if (arg->bundle->radius.alive.interval && !arg->bundle->radius.cfg.file) {
                                                ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~

In all cases, the file field of struct radius is a char array, but the
intent was to check whether the string is empty, so add an indirection
to achieve that.  Use a similar approach for the sockname field of
struct server.

Submitted by:	Christoph Mallon <christoph.mallon@gmx.de> (via private mail)

PR:		151400
Submitted by:	Aragon Gouveia - aragon at phat dot za dot net with minor fixes
MFC after:	3 weeks