merge -c 1508086 FIXES: HADOOP-9698. [RPC v9] Client must honor server's SASL negotiate response (daryn)


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1508088 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd