PR/46601 - Jim Bernard -- add support for rc_directories

branches: 1.8.58; 1.8.60;
Add two new rc.conf(5) variables:
rc_rcorder_flags extra flags to rcorder(8) in /etc/rc
rcshutdown_rcorder_flags extra flags to rcorder(8) in /etc/rc.shutdown

This can be used to specify extra directories to search for rc.d scripts in.
For example, adding the following to rc.conf(5):
rc_rcorder_flags="/usr/pkg/etc/rc.d/*"
rcshutdown_rcorder_flags="/usr/pkg/etc/rc.d/*"
will add the files in /usr/pkg/etc/rc.d to the list of files that rcorder(8)
uses to build the list of scripts to start or stop.

I proposed this functionality on tech-userlevel@ over one month ago.
Closes the recent [misc/16888], which asked for a similar feature.

use reverse_list() (from rc.subr) to reverse the list

- Implement an optional global watchdog timeout for rc.shutdown, which is
enabled by setting $rcshutdown_timeout to a number of seconds to wait for
before terminating rc.shutdown. This is disabled by default.
- Use symbolic names rather than numbers when defining a trap.
- Improve some comments.

- describe what rc.shutdown does, and what invokes it
- remove `.sh' suffix on script name in description

run rcorder with `-k shutdown', so that only the scripts with a
`shutdown' keyword get run at shutdown time.

branches: 1.3.4;
if checkyesno do_rcshutdown, run scripts in /etc/rc.d/* in the
reverse order returned by rcorder

Check for location of xdm's pid file as suggested by Simon Burge.
Fixes PR misc/6828 by Paul Goyette.

A basic /etc/rc.shutdown. Bails out if do_rcshutdown!=YES in /etc/rc.conf
(default is YES). Kills xdm and waits for it to terminate if it was enabled
in rc.conf (based on a code snippet from Ignatios).

pull up revs 1.4
approved by: thorpej

1.4:
run rcorder with `-k shutdown', so that only the scripts with a
`shutdown' keyword get run at shutdown time.

Pull up revision 1.9 (requested by jnemeth in ticket #375).

PR/46601 - Jim Bernard -- add support for rc_directories

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