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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Allow for MTU sizes of up to ETHER_MAX_LEN_JUMBO (i.e. 9018) bytes to be
configured on ng_eiface ifnets. The default MTU remains unchanged at
1500 bytes.

Mark ng_eiface ifnets as IFCAP_VLAN_MTU capable, so that the associated
vlan(4) ifnets may use full-sized Ethernet MTUs (1500 bytes).

MFC after: 3 days

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.

Added ASCII version of the NGM_EIFACE_GET_IFNAME message, "getifname".

Whitespace and "const" changes to reduce diffs to RELENG_4.
(Gives the same object when compiled without NETGRAPH_DEBUG.)

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

Use the (now standard) Ethernet address parse type.

MFS: Change interface name from "nge" to "ngeth" to avoid conflict
with nge(4).

Use a single style of multiple inclusion protection for Netgraph headers.

Reviewed by: archie, harti, emax

Fix GCC warnings caused by initializing a zero length array. In the process,
simply things a bit by getting rid of 'struct ng_parse_struct_info' which
was useless because it only contained one field.

MFC after: 2 weeks

slight cleanups during testing.

Add a node that looks to all the word like an ethernet but delivers its
ehternet frames to a netgraph hook.

Submitted by: "Vitaly V. Belekhov" <vitaly@riss-telecom.ru>
translated to 5.0 by me. man page not yet written.

This node still needs a little work.. don't use yet. Not yet linked into
the build.