sys: Remove $FreeBSD$: one-line .c comment pattern

Remove /^/[*/]\s*\$FreeBSD\$.*\n/

sys: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

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.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

Remove more constants related to static sysctl nodes. The MAXID constants
were primarily used to size the sysctl name list macros that were removed
in r254295. A few other constants either did not have an associated
sysctl node, or the associated node used OID_AUTO instead.

PR: ports/184525 (exp-run)

Remove most of the remaining sysctl name list macros. They were only
ever intended for use in sysctl(8) and it has not used them for many
years.

Reviewed by: bde
Tested by: exp-run by bdrewery

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.

First steps towards IPSec cleanup.

Make the kernel side of FAST_IPSEC not depend on the shared
structures defined in /usr/include/net/pfkeyv2.h The kernel now
defines all the necessary in kernel structures in sys/netipsec/keydb.h
and does the proper massaging when moving messages around.

Sponsored By: Secure Computing

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

"Fast IPsec": this is an experimental IPsec implementation that is derived
from the KAME IPsec implementation, but with heavy borrowing and influence
of openbsd. A key feature of this implementation is that it uses the kernel
crypto framework to do all crypto work so when h/w crypto support is present
IPsec operation is automatically accelerated. Otherwise the protocol
implementations are rather differet while the SADB and policy management
code is very similar to KAME (for the moment).

Note that this implementation is enabled with a FAST_IPSEC option. With this
you get all protocols; i.e. there is no FAST_IPSEC_ESP option.

FAST_IPSEC and IPSEC are mutually exclusive; you cannot build both into a
single system.

This software is well tested with IPv4 but should be considered very
experimental (i.e. do not deploy in production environments). This software
does NOT currently support IPv6. In fact do not configure FAST_IPSEC and
INET6 in the same system.

Obtained from: KAME + openbsd
Supported by: Vernier Networks