Thread saftey lock for mod_rewrite's cache... I'm sure others will have
  some 'better ideas' but this will work for now.

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


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91612 13f79535-47bb-0310-9956-ffa450edef68