once more with feeling

obj was set before the mutex so someone could have came and updated h->cache_obj
between us setting obj, and useing it.
running now for 10 minutes without core (a record!)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@93379 13f79535-47bb-0310-9956-ffa450edef68