Remember an authenticated user during internal redirects if the

redirection target is not access protected and pass it
to scripts using the REDIRECT_REMOTE_USER environment variable.

PR: 10678, 11602.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@100604 13f79535-47bb-0310-9956-ffa450edef68