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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

net: clean up empty lines in .c and .h files

sys: 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.

Upgrade the netgraph vlan node to support 802.1q, encapsulation type,
PCP and CFI fields.

* Ethernet_type for VLAN encapsulation is tunable, default is 0x8100;
* PCP (Priority code point) and CFI (canonical format indicator) is
tunable per VID;
* Tunable encapsulation to support 802.1q
* Encapsulation/Decapsulation code improvements

New messages have been added for this netgraph node to support the
new features.

However, the legacy "vlan" id is still supported and compiled in by
default. It can be disabled in a future release.

TODO:

* Documentation
* Examples

PR: kern/161908
Submitted by: Ivan <rozhuk.im@gmail.com>

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

- Import the HEAD csup code which is the basis for the cvsmode work.

Use variable-sized arrays where appropriate.

Netgraph node type for IEEE 802.1Q VLAN tagging.