Implement apr_proc_detach changes and allow -DNO_DETACH in the multi-process

Implement apr_proc_detach changes and allow -DNO_DETACH in the multi-process
mode to not "daemonize" while detaching from the controlling terminal.
This is necessary for Apache to work with process-management tools like
AIX's "System Resource Controller" as well as Dan Bernstein's "daemontools".

What this means is apache must _NOT_ be a process group leader if called
with the -DNO_DETACH flag.

Submitted from:     Jos Backus <josb@cncdsl.com>
Edited/Reviewed by: Aaron Bannert

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@93535 13f79535-47bb-0310-9956-ffa450edef68