Digest is mostly supported, for all the good it does.

PR: 2715
Obtained from:
Submitted by:	Youichirou Koga <y-koga@jp.FreeBSD.org>
Reviewed by:


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@81827 13f79535-47bb-0310-9956-ffa450edef68