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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Node constructor methods are supposed to be called in syscall
context always. Convert nodes to consistently use M_WAITOK flag
for memory allocation.

Reviewed by: julian

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

Retire the MALLOC and FREE macros. They are an abomination unto style(9).

MFC after: 3 months

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

Plug item leak in case when not all hooks are connected.

Found by: David Vos <david.vos gmail.com>

Return EINVAL for incorrect hook names.

PR: kern/81349
Submitted by: Wojciech A. Koszek

bzero() -> M_ZERO.

Switch to using C99 sparse initialisers for the type methods array.
Should make no binary difference.

Submitted by: Gleb Smirnoff <glebius@cell.sick.ru>
Reviewed by: Harti Brandt <harti@freebsd.org>
MFC after: 1 week

Update to C99, s/__FUNCTION__/__func__/,
also don't use ANSI string concatenation.

General cleanup providing better style(9) conformance and generally
improved readability. The two real functional changes are that
netgraph now sees this as the "split" node type rather then the
"ng_split" node type and that meta data is passed through without
processing rather then being dropped.

Reviewed by: jhb, julian
MFC after: 7 weeks

Add a 'splitter' node to separate a bidirectional
packet flow into two unidirectional flows.

Part of a suite of nodes developed for packet flow control.
More to follow as I have time to port them to 5.x or
as others do so. The ipfw node will be the hardest..

Submitted by: "Vitaly V. Belekhov" <vitaly@riss-telecom.ru>