libc: Purge unneeded cdefs.h

These sys/cdefs.h are not needed. Purge them. They are mostly left-over
from the $FreeBSD$ removal. A few in libc are still required for macros
that cdefs.h defines. Keep those.

Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D42385

Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

libc/net/nscachedcli.c: remove write-only variables

Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Style cleanup.

libc: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified 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.

libc: spelling fixes.

Mostly on comments.

libc: Use SOCK_CLOEXEC for various internal file descriptors.

This change avoids undesirably passing some internal file descriptors to a
process created (fork+exec) by another thread.

Kernel support for SOCK_CLOEXEC was added in r248534, March 19, 2013.

libc: Avoid SIGPIPE when nscd closes the connection unexpectedly.

It is almost always a bug if nscd closes the connection unexpectedly but
programs should not be killed with SIGPIPE for it.

Reviewed by: bushman
Tested by: Jan Beich
MFC after: 1 week

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.

Use _kevent() instead of kevent().

Requested by: nork

Fix alignment problem on AMD64.

Reported by: Pascal Hofstee <caelian__at__gmail.com>
Submitted by: Michael Bushkov <bushman__at__rsu.ru>
Tested by: Pascal Hofstee <caelian__at__gmail.com>

- Extend the nsswitch to support Services, Protocols and Rpc
databases.
- Make nsswitch support caching.

Submitted by: Michael Bushkov <bushman__at__rsu.ru>
Sponsored by: Google Summer of Code 2005