Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56825
Enable pre-emptive authentication to work with the SSL authenticator. Based on a patch by jlmonteiro.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1617445 13f79535-47bb-0310-9956-ffa450edef68