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, which incorporates the following changes
since the last imported OpenBSM release:

OpenBSM 1.1

- Change auditon(2) parameters and data structures to be 32/64-bit architecture
independent. Add more information to man page about auditon(2) parameters.
- Add wrapper functions for auditon(2) to use legacy commands when the new
commands are not supported.
- Add default for 'expire-after' in audit_control to expire trail files when
the audit directory is more than 10 megabytes ('10M').
- Interface to convert between local and BSM fcntl(2) command values has been
added: au_bsm_to_fcntl_cmd(3) and au_fcntl_cmd_to_bsm(3), along with
definitions of constants in audit_fcntl.h.
- A bug, introduced in OpenBSM 1.1 alpha 4, in which AUT_RETURN32 tokens
generated by audit_submit(3) were improperly encoded has been fixed.
- Fix example in audit_submit(3) man page. Also, make it clear that we want
the audit ID as the argument.
- A new audit event class 'aa', for post-login authentication and
authorization events, has been added.

Obtained from: TrustedBSD Project
Sponsored by: Apple, Inc.

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.