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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

powerpc: clean up empty lines in .c and .h files

sys/powerpc: further 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.

Add support for Power Button PMU events on non-ADB macs, such as aluminum
PowerBooks.

MFC after: 2 weeks
Relnotes: yes

Add PMU-based CPU frequency scaling. This method is used on most Titanium
PowerBooks.

MFC after: 1 month

Add a devd notification for closing/opening the lid on PowerBooks and iBooks.

Approved by: nwhitehorn (mentor)

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

Add the ability to control the sleep LED with led(4). Adding this fairly
useless feature gives us a reasonably complete PMU implementation.

Add facilities to pmu(4) to interrogate battery status on Apple PowerPC
laptops. This includes battery presence detection, charging status, current
and voltage readouts, and charge level indication. The sysctl interface
is somewhat ACPI-like.

Add ADB support. This provides support for the external ADB bus on the PowerMac
G3 as well as the internal ADB keyboard and mice in PowerBooks and iBooks. This
also brings in Mac GPIO support, for which we should eventually have a better
interface.

Obtained from: NetBSD (CUDA and PMU drivers)