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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

sys/netgraph: spelling fixes in comments.

No functional change.

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.

Remove ng_connect_t where it is unused. Probably it remained from ng_source.c.

Make M_NETGRAPH_ETF static

/* -> /*- for license, minor formatting changes

Having moved metadata usage to mbuf tags, remove code that supports
the old way of doing it.

Submitted by: Gleb Smirnoff <glebius@cell.sick.ru>

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

Fixed panic on hook disconnection that previous revision has introduced.

Fixed two memory leaks.

Reviewed by: harti

Fix GCC warnings caused by initializing a zero length array. In the process,
simply things a bit by getting rid of 'struct ng_parse_struct_info' which
was useless because it only contained one field.

MFC after: 2 weeks

A node that allows ethernet type packets to be filtered to different
hooks depending on ethertype. Great for prototyping protocols.
connects to the lower and upper hooks of an ethernet type of node.

Obtained from: Monzoon Networks.
Thanks to Andre Oppermann, May 2001.