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

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

mail: make The Dragonfly Mail Agent (dma) the default mta.

dma accepts mail from a local Mail User Agent (MUA) and delivers it
locally or to a smarthost for delivery. dma does not accept inbound
mail (i.e., it does not listen on port 25) and is not intended to
provide the same functionality as a full MTA like postfix or sendmail.
It is intended for use cases such as delivering cron(8) mail. which
is the default configuration and usage of sendmail in the default
setup of the base system.

In order to switch the default from sendmail to dma, we teach
mailwrapper to fallback on dma directly if the mailer.conf file cannot
be opened.
We install by default a mailer.conf file which points at dma
We install a mailer.conf file for sendmail in the examples.

Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D37035

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.

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.

Merge from OpenBSD:
o Realloc memory leak fixed which won't matter but would trigger purify
o Default to sendmail when no mailer.conf exists.

Fixed bugs in OpenBSD version:
o Add NULL termination in the right place.

Also put back the err. free shouldn't touch errno.

Pointed out by: theo de raadt (except the NULL bug :-)

Move mailer.conf to /etc/mail at obrien's request.

Make mailwrapper build