Fix segfault at startup when the startup fails before running the post config

hook. We were setting the hash table cleanup in the create_per_server_config
hook and allocating the hash table in the post config hook. Move the register_cleanup
to the post_config hook


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95532 13f79535-47bb-0310-9956-ffa450edef68