save-entropy: Add manual page

Succinct manual page for save-entropy(8).

PR: 223998
Reported by: AJ Jordan <alex+freebsd@strugee.net>
Reviewed by: carlavilla@, delphij@, lwhsu@, pauamma_gundo.com
Approved by: delphi, lwhsu (src)
Differential Revision: https://reviews.freebsd.org/D41768

Remove $FreeBSD$: one-line sh pattern

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

Remove NO_OBJ

For meta mode we will want objdirs.

Differential Revision: D2748
Reviewed by: brooks imp

We do want objdir

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.

Start the dreaded NOFOO -> NO_FOO conversion.

OK'ed by: core

Mark bits that do not require an object directory as such.

beforeinstall -> SCRIPTS.

Add a system to save entropy from /dev/random periodically so that
it can be used to reseed at boot time. This will greatly increase
the chances that there will be sufficient entropy available at
boot time to prevent long delays.

For /etc/rc, remove the vmstat and iostat runs from the attempt
to provide some cheesy randomness if the files fail, since
those programs are dynamically linked, and ldd seems to want
some randomness to do its magic.

Guidance and parameters for this project were provided by
Mark Murray, based on the requirements of the Yarrow
algorithm. Some helpful suggestions for implementation
(including the tip about iostat and vmstat) were provided
by Sheldon Hearn. All blame for problems or mistakes is
mine of course.