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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

sys: general 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.

No functional change intended.

Add a DFS debugging mode which is useful when doing automated DFS
compliance testing.

In order to allow for radar pattern matching to occur, the DFS CAC/NOL
handling needs to be made configurable. This commit introduces a new
sysctl, "net.wlan.dfs_debug", which controls which DFS debug mode
net80211 is in.

* 0 = default, CSA/NOL handling as per normal.
* 1 = announce a CSA, but don't add the channel to the non-occupy list
(NOL.)
* 2 = disable both CSA and NOL - only print that a radar event occured.

This code is not compiled/enabled by default as it breaks regulatory
handling. A user must enable IEEE80211_DFS_DEBUG in their kernel
configuration file for this option to become available.

Obtained from: Atheros

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

Fix definition of IEEE80211_CHAN_MAX; it was defined as 255 but
really was meant to be 256. Adjust usage accordingly and replace
bogus usage of this value in checking IEEE channel #'s.

NB: this causes an ABI change; ifconfig must be recompiled

- Import the HEAD csup code which is the basis for the cvsmode work.

Multi-bss (aka vap) support for 802.11 devices.

Note this includes changes to all drivers and moves some device firmware
loading to use firmware(9) and a separate module (e.g. ral). Also there
no longer are separate wlan_scan* modules; this functionality is now
bundled into the wlan module.

Supported by: Hobnob and Marvell
Reviewed by: many
Obtained from: Atheros (some bits)