sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

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

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.

net80211: fix more compiler warnings.

ieee80211.c:
add_chanlist(): 'error' variable will be uninitialized if
no channels were passed; return '0' instead.
ieee80211_action.c:
ieee80211_send_action_register(): drop 'break' after 'return'.
ieee80211_crypto_none.c:
none_encap(): 'keyid' is not used in non-debug builds; hide it
behind IEEE80211_DEBUG ifdef.
ieee80211_freebsd.c:
Staticize global 'ieee80211_debug' variable (used only in this
file).
ieee80211_hostap.c:
Fix a comment (associatio -> association).
ieee80211_ht.c:
ieee80211_setup_htrates(): initialize 'maxunequalmcs' to 0 to mute
compiler warning.
ieee80211_hwmp.c:
hwmp_recv_preq(): copy 'prep' between conditional blocks to fix
-Wshadow warning.
ieee80211_mesh.c:
mesh_newstate(): remove duplicate 'ni' definition.
mesh_recv_group_data(): fix -Wempty-body warning in non-debug
builds.
ieee80211_phy.c:
ieee80211_compute_duration(): remove 'break' after panic() call.
ieee80211_scan_sta.c:
Hide some TDMA-specific macros under IEEE80211_SUPPORT_TDMA ifdef
adhoc_pick_bss(): remove 'ic' pointer redefinition.
ieee80211_sta.c:
sta_beacon_miss(): remove 'ic' pointer redefinition.
ieee80211_superg.c:
superg_ioctl_set80211(): drop unreachable return.

Tested with clang 3.8.0, gcc 4.6.4 and gcc 5.3.0.

net80211: drop some unused variables / local macros

Most of them left after some commits (r178354, r191544, r287197 etc.);
some were never used.

Found by: Clang Static Analyzer

[net80211] rename 11n rate macros into a useful spot

* begin moving the 11n macros out of ieee80211_phy.c and
into a header so they can be used elsewhere.

* rename some of them into the IEEE80211_* namespace.

* convert HT_RC_2_MCS() to work with three-stream rates.

Provide includes that are needed in these files, and before were read
in implicitly via if.h -> if_var.h pollution.

Sponsored by: Netflix
Sponsored by: Nginx, Inc.

Replace the homegrown implementation of nitems() with calls to nitems()
(param.h).

Operating systems that don't have nitems() can easily define it on their own
net80211 OS-specific header file.

Discussed with: adrian

Implement basic 802.11n awareness in the PHY and AMRR rate control code.

* Add 802.11n 2ghz and 5ghz tables, including legacy rates and up to
MCS23 rates (3x3.)

* Populate the rate code -> rate index lookup table with MCS _and_
normal rates, but _not_ the basic rate flag. Since the basic rate flag
is the same as the MCS flag, we can only use one.

* Introduce some accessor inlines that do PLCP and rate table lookup/access
and enforce that it doesn't set the basic rate bit. They're not
designed for MCS rates, so it will panic.

* Start converting drivers that use the rate table stuff to use the
accessor inlines and strip the basic flag.

* Teach AMRR about basic 11n - it's still as crap for MCS as it is
being used by iwn, so it's not a step _backwardS_.

* Convert iwn over to accept 11n MCS rates rather than 'translate' legacy
to MCS rates. It doesn't use a lookup table any longer; instead it's a
function which takes the current node (for HT parameters) and the
rate code, and returns the hardware PLCP code to use.

Tested:

* ath - it's a no-op, and it works that way
* iwn - both 11n and non-11n

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

use 1/2 and 1/4 rate phy types to simplify txtime calculation

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

use c99 syntax for initializers; this silences
warnings with picky compiler settings

Update PLCP<->rate mapping support:
o correct mapping of CCK rates to PLCP; was using nonstandard Ralink
values which just happened to also be used by Zydas (so went unnoticed)
o change ieee80211_plcp2rate api to take a phy type instead of a flag
that indicates ofdm/!ofdm
o update drivers to match (restore per-driver code to map rate->PLCP)

Reviewed by: sephe, weongyo, thompsa

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)