Refactor releasing the child processes by eliminating the

time lookup, eliminating the bogus/misimplemented function,
and introducing fairness to release any dead threads before
getting hung up on releasing longer lived threads.

Also pick up the time-to-wait from the server global timeout.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@573103 13f79535-47bb-0310-9956-ffa450edef68