This patch optimizes away some strlen and strcat calls in

ap_directory_walk.  The strlen calls, in particular, had
ranked as a top bottleneck in the usr-space code in recent
performance profiling.

Submitted by:	Brian Pane <bpane@pacbell.net>
Reviewed by:	Justin Erenkrantz


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91746 13f79535-47bb-0310-9956-ffa450edef68