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

Remove /^/[*/]\s*\$FreeBSD\$.*\n/

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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

Remove unneeded checks for prelen.

In order to determine the type of a compressed file, we have to read
in the first four bytes which may also be important for decompression
purposes, to do that we would pass the buffer that we have already
read in, along with the size of it.

Rename header1 to fourbytes to make that explicit, and remove all
checks for prelen.

Reported by: cem
Reviewed by: cem
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D24034

Remove "All rights reserved" from my files.

See r333391 for the rationale.

MFC after: 1 week

various: 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.

Support SIGINFO.

Obtained from: NetBSD
MFC after: 2 weeks

style(9) indent changes, no actual code change.

MFC after: 2 weeks

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

Correct some typos in comments, no functional changes.

Check return value of dup(), it could be -1 when the system is running
out of file descriptors for instance.

Found with: Coverity Prevent(tm)
CID: 6084
MFC after: 1 month

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

Add support for uncompressing pack(1)'ed files. Pack(1) is a program found
in some commercial Unix systems, which utilizes Huffman minimum redundancy
code tree to compress files. This implementation supports the "new" pack
format only, just like GNU gzip did.

Thanks for oliver@'s archive set which I can test against, and Mingyan Guo
for providing helpful review of my code.

PR: bin/109567
MFC after: 1 month