Remove $FreeBSD$: one-line sh pattern

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

rc.resume: remove obsolete comment

Reviewed by: markj
Approved by: markj (mentor)
Differential Revision: https://reviews.freebsd.org/D40235

rcorder(8): add support for /etc/rc.resume, so it calls "rcorder -k resume"
and runs scripts containing "KEYWORD: resume" with single "resume" argument.

Working example is the port sysutils/cpupdate that defines
extra_commands="resume" to reload CPU microcode cleared
by suspend/resume sequence.

This change does nothing for a system having no scripts with KEYWORD: resume.

MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D15247

Move the rc framework out of sbin/init into libexec/rc.

The reasons for this are forward looking to pkgbase:
* /sbin/init is a special binary; try not to replace it with
every package update because an rc script was touched.
(a follow-up commit will make init its own package)
* having rc in its own place will allow more easy replacement
of the rc framework with alternatives, such as openrc.

Discussed with: brd (during BSDCam), kmoore
Requested by: cem, bz
PR: 231522
Approved by: re (gjb)