sys: 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

(s)tty: add support for IUTF8 input flag

This patch adds the necessary kernel and stty code to support setting
the IUTF8 flag for ttys. It is the first of two patches that fix
backspace behaviour for UTF-8 encoded characters when in canonical mode.

Reported by: christos
Reviewed by: christos, imp
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D42066

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

Remove /^\s*\*+\s*\$FreeBSD\$.*$\n/

termios: add more speeds

A lot of small arm64 gadgets are using 1500000 as console speed.
While cu can perfectly deal with this some 3rd party software, e.g.,
comms/conserver-con add speeds based on B<n> being defined.
Having it defined here simplifies enhancing other software.

Obtained-from: NetBSD sys/sys/termios.h 1.36
MFC-after: 2 weeks
Reviewed-by: philip (,okayed by imp)
Differential Revision: https://reviews.freebsd.org/D29209

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

Some devices take undesired actions when RTS and DTR are
asserted. Some development boards for example will reset on DTR,
and some radio interfaces will transmit on RTS.

This patch allows "stty -f /dev/ttyu9.init -rtsdtr" to prevent
RTS and DTR from being asserted on open(), allowing these devices
to be used without problems.

Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D20031

sys: 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.

Relax visibility for some termios symbols.

They are defined by XSI or newer SUS.
This is a follow-up to r318780.

Reported by: jbeich
Obtained from: DragonflyBSD commit e08b3836c962
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Use __BSD_VISIBLE test instead checking for absense of _POSIX_SOURCE.

The Termios headers <termios.h> and <sys/_termios.h> used sometimes
_POSIX_SOURCE directly to determine if a thing should be exposed to
the user. This circumvented the feature mechanisms of <sys/cdefs.h>.

Submitted by: Sebastian Huber <sebastian.huber@embedded-brains.de>
MFC after: 2 weeks

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

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

Decompose <sys/termios.h>.

The <sys/termios.h> header file is hardlinked to <termios.h>. It
contains both the structures and the flag definitions, but also the C
library interface that's implemented by the C library.

This header file has the typical problem of including too many random
things and being badly ordered. Instead of trying to fix this, decompose
it into two header files:

- <sys/_termios.h>, which contains struct termios and the flags.
- <termios.h>, which includes <sys/_termios.h> and contains the C
library interface.

This means userspace has to include <termios.h> for struct termios,
while kernelspace code has to include <sys/tty.h>. Also add a
<sys/termios.h>, which prints a warning message before including
<termios.h>. I am aware that there are some applications that use this
header file as well.