Fix directory indexing so that if an index file encounters an error

that is not 404, it returns that error instead of a directory index.
This was causing unsafe behavior.

Reviewed by: Brian Behlendorf, Aram Mirzadeh, Paul Sutton


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@77091 13f79535-47bb-0310-9956-ffa450edef68