Removal of the old rc system from -current

[Scot W. Hetzel]

From: "Doug Barton" <DougB at freebsd.org>
> 2. Backport /etc/rc.subr to RELENG_4 prior to 4.9-Release. The purpose
> here is to allow ports authors to make use of the rcNG system for their
> startup scripts, and to possibly allow us to backport major features that
> just work better in the NG framework.
>
I started porting my ports rc scripts to work on both rcNG and rcOG systems.
In this process I found the ideal solution for the ports rc.d script:

    1. define default port variables in the script
    2. check for /etc/rc.subr
        a. if rc.subr exists, use rcNG style
        b. if rc.subr not exists
            1. source /etc/defaults/rc.conf (or /etc/rc.conf)
            2. use rcOG style

This way we can keep compatibility with previous releases as well in the
ports tree. (see ports/security/cyrus-sasl/files/*.sh & PR 51505). Then
after a period of time we could drop the rcOG support from the ports tree.

Another option would be to have bsd.port.mk detect that /etc/rc.subr doesn't
exist, and then install a rc.subr on these older systems.

Scot