MFC r255521, r255526, r255707:

MFC r255521, r255526, r255707:

r255521 (jmg):

add support for writing the pid of the daemon program to a pid file so
that daemon can be used w/ rc.subr and ports can use the additional
functionality, such as keeping the ldap daemon up and running, and have
the proper program to signal to exit.

PR:		bin/181341
Submitted by:	feld

r255526 (joel):

mdoc: remove EOL whitespace.

r255707:

1. Properly clean pid files in the case of the error.
2. Write the supervisor pid before the restart loop, so we don't
   uselessly rewrite it after every child restart.
3. Remove duplicate ppfh and pfh initialization.

git-svn-id: svn://svn.freebsd.org/base/stable/8@256026 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f