usr.bin: Remove ancient SCCS tags.

Remove ancient SCCS tags from the tree, automated scripting, with two
minor fixup to keep things compiling. All the common forms in the tree
were removed with a perl script.

Sponsored by: Netflix

Remove $FreeBSD$: two-line .c pattern

Remove /^#include\s+<sys/cdefs.h>.*$\n\s+__FBSDID\("\$FreeBSD\$"\);\n/

Add stat counter for ipv6 atomic fragments

Add a stat counter to track ipv6 atomic fragments. Atomic fragments can be
generated in response to invalid path MTU values, but are also a potential
attack vector and considered harmful (see RFC6946 and RFC8021).

While here add tracking of the atomic fragment counter to netstat and systat.

Reviewed by: tuexen, jtl, bz
Approved by: jtl (mentor), bz (mentor)
Event: Aberdeen hackathon 2019
Differential Revision: https://reviews.freebsd.org/D17511

Fix printing of 64-bit counters on 32-bit ppc platforms.

Several statistic counters are uint64_t values and are printed by systat
using %lu. This results in displaying wrong numbers. Use PRIu64 instead.
While there, print variables of size_t using %zd.

MFC after:i 3 days
Differential Revision: https://reviews.freebsd.org/D17838

General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

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.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

Renumber copyright clause 4

Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by: Jan Schaumann <jschauma@stevens.edu>
Pull Request: https://github.com/freebsd/freebsd/pull/96

Make systat(1) accept fractional number of seconds.
Make old alarm(3)-based code use select(2).

MFC after: 2 weeks

Remove the advertising clause from UCB copyrighted files in usr.bin. This
is in accordance with the information provided at
ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change

Also add $FreeBSD$ to a few files to keep svn happy.

Discussed with: imp, rwatson

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

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.

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

ANSIfy and remove register.

Resulting binary verified with strip(1)+md5(1).

Remove trailing whitespace.

Submitted by: Se=E1n Farley <sean-freebsd at farley dot org>
PR: bin/81874

Show the load average in the tcp display (it was already shown, perhaps
not very usefully, in all other displays). This was the original point
of the PR.

Move the load average up by 2 so that it starts in row 0 for all windows
(2 lines above it were wasted for all other windows except vmstat).
Move everything below it up by 2 or 3 (3 for icmp and icmp6 which had
an extra blank line due from not compensating for the foot-shooting in
note (3); only ip and ip6 compensated). Reduce the magic numbers related
to this.

Notes by the submitter:
%%%
1. All the subwin() calls are identical using #define MAINWIN_ROW 3
(systat.h).
2. The load average is at the top of the window.
3. Each display starts on the fourth line. I made changes to those
displays that shifted the start line (i.e., icmp). This entailed a
lot of changes within the comments at the top of those displays.
4. For ip6, I shifted the "Input next-header histogram" column down one
row to separate it from "IPv6 Output". I raised "bad scope packets"
and "address selection failed" up one row to stay with "IPv6 Input"
(valid?). They were down one row to probably line up at the bottom,
but I think they should stick with their fellow items in a column.
5. I condensed ifstat a bit. It had a lot of empty rows.
%%%

Submitted by: Se=E1n Farley <sean-freebsd at farley dot org>
PR: bin/81874

Add ip6 and icmp6 displays to systat.

MFC after: 2 weeks