Backports: r1635762

Submitted By: Edward Lu <Chaosed0 gmail.com>
Support custom ErrorDocuments for HTTP 501 and 414 status codes.
PR 57167 [Edward Lu <Chaosed0 gmail.com>]


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x-merge-http-strict@1775718 13f79535-47bb-0310-9956-ffa450edef68