Add a missing errordir entry in the Debian config.layout.

PR: 10067
Obtained from:  Dirk-Jan Faber <dirk-jan@selwerd.nl>


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@93762 13f79535-47bb-0310-9956-ffa450edef68