kernel - Add reapctl() system call for managing sub-processes (3) -> procctl()

* After discussions, rename reapctl() -> procctl() and adjust
  the API to be compatible with FreeBSD.

* bapt will implement the same exact feature in FreeBSD via procctl().
svc - Initial commit, preliminary service manager

* This is a preliminary service manager frontend and demon.
  It is not yet ready for prime-time (lots of support bits
  are missing).

* The main premise of this program is to be able to create
  and manage services in a more robust fashion, obtain status,
  log recent output or all output, and so forth.

  Among the many features, this program uses the new REAPER support
  to ensure that all processes related to the service can be accounted
  for.

* Includes a comprehensive manual page that lists all target features
  (many of which are not yet implemented as of this commit).
svc - misc improvements

* Disallow extremely dangerous command sequences like 'svc exit' without
  a label (which would wildcard everything).

* Allow the label to be specified as 'all' for when you really want to
  operate on everything with a dangerous command.

* Clean up the socket and pid files on normal exit/kill, even if the
  service is not present.

* Add 'help' directive and -h option to cover our bases.