svn merge -c 1512314 from trunk to branch-2 to fix HADOOP-9672.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1512315 13f79535-47bb-0310-9956-ffa450edef68
merge -c 1512380 FIXES: HADOOP-9789.  Support server advertised kerberos principals (daryn)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1512381 13f79535-47bb-0310-9956-ffa450edef68