Rework locking on timeout_mutex. We now drop (and reaquire) the lock inside...

Rework locking on timeout_mutex.  We now drop (and reaquire) the lock inside the while loops.  This is the least line of code changes to stop a dead lock between the queue in push2worker (a blocking function) and the timeout_mutex.  These two timeout list iterations should be rewritten with better locking rules, but for now this should fix the bug, without rewriting the entire function.
PR: 41712


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@567852 13f79535-47bb-0310-9956-ffa450edef68