Prevent the source code for CGIs from being revealed when using

mod_vhost_alias and the CGI directory is under the document root
and a user makes a request like http://www.example.com//cgi-bin/cgi
as reported in <news:960999105.344321@ernani.logica.co.uk>


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85575 13f79535-47bb-0310-9956-ffa450edef68