HDFS-6755. There is an unnecessary sleep in the code path where DFSOutputStream#close gives up its attempt to contact the namenode (mitdesai21 via cmccabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1613523 13f79535-47bb-0310-9956-ffa450edef68