Get mod_cgid to use apr calls for creating the actual CGI process.

This also allows mod_cgid to use ap_os_create_priviledged_process,
thus allowing for SuExec execution from mod_cgid.  Currently, we do
not support everything that standard SuExec supports, but at least
it works minimally now.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@87524 13f79535-47bb-0310-9956-ffa450edef68