Add "-k start|startssl|restart|graceful|stop" support to httpd

Add "-k start|startssl|restart|graceful|stop" support to httpd
for the Unix MPMs.  These have semantics very similar to the
old apachectl commands of the same name.

The use of stderr/stdout and exit status for error conditions
needs to be revisited.  For now it matches apachectl behavior.

Justin Erenkrantz got the ball rolling with this feature.  Some
of his support code was used unchanged.  Other code was shuffled
around and modified or rewritten.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95237 13f79535-47bb-0310-9956-ffa450edef68