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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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 powermac: Remove unused devclass arguments to DRIVER_MODULE.

powerpc: Fix programmer's switch driver and add to GENERIC

Older G4 and G3 models have a programmer's switch that can be used to
generate an interrupt to drop into the debugger.

This code hadn't been tested for a long time. It had been broken back
in 2005 in r153050.

Repair and modernize the code and add it to GENERIC.

Reviewed by: jhibbits (approved w/ removal of unused sc_dev var)
Sponsored by: Tag1 Consulting, Inc.
Differential Revision: https://reviews.freebsd.org/D29131

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.

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.

Add a new 'why' argument to kdb_enter(), and a set of constants to use
for that argument. This will allow DDB to detect the broad category of
reason why the debugger has been entered, which it can use for the
purposes of deciding which DDB script to run.

Assign approximate why values to all current consumers of the
kdb_enter() interface.

Make pswitch_intr() returns interrupt handling status.

Catch up with bus_setup_intr() modification and garbage collect a
reference to INTR_FAST.

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

Make this compile: add sys/module.h and KDBify.

Oops. Include opt_ddb.h.

Add a driver that attaches to the gpio node of macio and allows you to enter
DDB when the interrupt button (aka the "programmer's switch") is pressed.

This isn't unfortunately an NMI, but it's a handy way to get into DDB
quickly if needed.