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: mostly fixes to previous changes.

Introduce the recently approved BSD-1-Clause and replace 0BSD which
never did fit well our use cases.

Zero out a local variable also when PURIFY is not defined.
This silence a warning brought up by valgrind whenever if_nametoindex
is used. This was already discussed in PR 166483, but the code
committed in r234329 guards the initilization with #ifdef PURIFY.
Therefore, valgrind still complains. Since this code is not performance
critical, always zero out the local variable to silence valgrind.

PR: 166483
Discussed with: eadler@
MFC after: 4 weeks

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.

Use the LLINDEX macro to access the link-level I/F index. This makes
it possible to work with a different type for the sdl_index field --
it only requires a recompile.

Obtained from: Juniper Networks, Inc.

When searching for uninitialized memory usage add ensure that the entire
struct is set to zero.

PR: bin/166483
Submitted by: Roy Marples <roy@marples.name>
Reviewed by: delphij
Approved by: cperciva
MFC after: 3 days

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.

Back out the `hiding' of strlcpy and strlcat. Several people
vocally objected to this safety belt.

`Hide' strlcpy and strlcat (using the namespace.h / __weak_reference
technique) so that we don't wind up calling into an application's
version if the application defines them.

Inspired by: qpopper's interfering and buggy version of strlcpy

Eliminate 61 warnings emitted at WARNS=2 (leaving 53 to go).
Only warnings that could be fixed without changing the generated object
code and without restructuring the source code have been handled.

Reviewed by: /sbin/md5

try SIOCGIFINDEX 1st to be able to use network aliasing.

Submitted by: jlemon
Approved by: re

Use BSDi derived if_nametoindex(), if_indextoname(), if_nameindex()
and if_freenameindex().

Obtained from: KAME
MFC after: 2 weeks