The call to apr_explode_localtime() in mod_log_config is one of the more

expensive operations in the httpd.  This patch attempts to reduce the
overhead by caching the result for 15 seconds.

Submitted by:	Brian Pane <bpane@pacbell.net>
Reviewed by:	Cliff Woolley, Ryan Bloom, Dean Gaudet, Justin Erenkrantz


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91083 13f79535-47bb-0310-9956-ffa450edef68