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/

sysctlbyname(): restore access to user variables

The optimization of sysctlbyname() in commit d05b53e0baee7 had the
side-effect of not going through the fix-up for the user.* variables
in the previously called sysctl() function.

This lead to 0 or an empty strings being returned by sysctlbyname()
for all user.* variables.

An alternate implementation would store the user variables in the
kernel during system start-up. That would allow to remove the fix-up
code in the C library that is currently required to provide the actual
values.

This update restores the previous code path for the user.* variables
and keeps the performance optimization intact for all other variables.

Approved by: mjg
Reviewed by: kaktus
Differential Revision: https://reviews.freebsd.org/D34171

sysctlbyname(2): Remove temporary compatibility layer

Remove temporary compatibility layer introduced in r351729. More that 3 months
should be enough for everybody who runs HEAD to upgrade to the new kernel
already.

Reviewed by: imp, mjg (mentor)
Approved by: mjg (mentor)
Differential Revision: https://reviews.freebsd.org/D22958

Add sysctlbyname system call

Previously userspace would issue one syscall to resolve the sysctl and then
another one to actually use it. Do it all in one trip.

Fallback is provided in case newer libc happens to be running on an older
kernel.

Submitted by: Pawel Biernacki
Reported by: kib, brooks
Differential Revision: https://reviews.freebsd.org/D17282

Eliminate redundant variable.

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.

While there, trim some trailing whitespace.

Add proper const keywords to sysctl(3) parameters.

The `name' and `newp' arguments can be marked const, because the buffers
they refer to are never changed. While there, perform some other
cleanups:

- Remove K&R from sysctl.c.
- Implement sysctlbyname() using sysctlnametomib() to prevent
duplication of an undocumented kernel interface.
- Fix some whitespace nits.

It seems the prototypes are now in sync with NetBSD as well.

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

Fix SCM ID's.

$Id$ -> $FreeBSD$

Change a variable to type size_t to suit the sysctl prototype.

Add #include <string.h> to get prototypes.

Have sysctlbyname() take a const first arg (the ascii string)

sysctlbyname allows acces to sysctl variables by name.

The manpage has been sent to linquistic decontamination and will arrive
when released from the quarantine

Reviewed by: peter