pwait.1: add missing prompt and command in examples

Two examples showed '$?' alone on a line, which should be '$ echo $?'.
The third example got it right. Fix the first two.

Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

Remove deadlock in rc caused by pwait waiting for itself.

The following situation can trigger the deadlock:
1) Long time ago a_service was started through rc.d
2) We want to restart a_service and issue service a_service restart
3) rc.subr reads current process PID (via file or process),
sends TERM signal and runs pwait with PID harvested
4) a_service process dies very quickly so it's PID becomes available.
It is possible that while original process was running,
PID counter overflowed and pwait got assigned a_service's PID.

This patch ignores pid(s) to wait that are equal to pwait PID.

Reported by: Dan McGregor, Boris Lytochkin
Submitted by: Boris Lytochkin <lytboris at gmail.com>
Reviewed By: 0mp
MFC after: 2 weeks
PR: 218598
Differential Revision: https://reviews.freebsd.org/D28240

pwait(1): Add EXAMPLES section to man page

* Add small EXAMPLES section to the man page showing the different
flags and exit codes.

* Complete description for -v flag.

Approved by: manpages (bcr@)

Implement -o flag which tells pwait(1) to exit if any of the given processes
has terminated.

Sponsored by: Fudo Security

pwait: Add a -t flag to specify a timeout before exiting, and tests.

The exit status will be 124, as the timeout(1) utility uses.

Reviewed by: jilles
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D9697

Remove trailing whitespace per mdoc lint warning

Disussed with: gavin
No objection from: doc
Approved by: joel
MFC after: 3 days

Remove superfluous paragraph macro.

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

mdoc: order prologue macros consistently by Dd/Dt/Os

Although groff_mdoc(7) gives another impression, this is the ordering
most widely used and also required by mdocml/mandoc.

Reviewed by: ru
Approved by: philip, ed (mentors)

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.

MFC r199458: Add pwait utility, which waits for any process to terminate.

This is similar to the Solaris utility of the same name.

Some use cases:
* rc.subr's wait_for_pids
* interactive use, e.g. to shut down the computer when some task is done
even if the task is already running

Add pwait utility, which waits for any process to terminate.

This is similar to the Solaris utility of the same name.

Some use cases:
* rc.subr's wait_for_pids
* interactive use, e.g. to shut down the computer when some task is done
even if the task is already running

Discussed on: hackers@