sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\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.

Merge from contrib/openbsm to bring the kernel audit bits up to date with OpenBSM 1.2 alpha 4:

- remove $P4$
- fix a comment

Vendor import of OpenBSM 1.2-alpha4.

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

Vendor import of OpenBSM 1.1 alpha5, which incorporates the following
changes since the last imported OpenBSM release:

OpenBSM 1.1 alpha 5

- Stub libauditd(3) man page added.
- All BSM error number constants with BSM_ERRNO_.
- Interfaces to convert between local and BSM socket types and protocol
families have been added: au_bsm_to_domain(3), au_bsm_to_socket_type(3),
au_domain_to_bsm(3), and au_socket_type_to_bsm(3), along with definitions
of constants in audit_domain.h and audit_socket_type.h. This improves
interoperability by converting local constant spaces, which vary by OS, to
and from Solaris constants (where available) or OpenBSM constants for
protocol domains not present in Solaris (a fair number). These routines
should be used when generating and interpreting extended socket tokens.
- Fix build warnings with full gcc warnings enabled on most supported
platforms.
- Don't compile error strings into bsm_errno.c when building it in the kernel
environment.
- When started by launchd, use the label com.apple.auditd rather than
org.trustedbsd.auditd.

Obtained from: TrustedBSD Project
Sponsored by: Apple Inc.