Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=55851
Enable SPNEGO to work with IBM JDKs.
Based on a patch by Arunav Sanyal.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1548695 13f79535-47bb-0310-9956-ffa450edef68