HDFS-6084. DFSConfigKeys.DFS_BLOCKREPORT_INTERVAL_MSEC_DEFAULT is not updated with latest block report interval of 6 hrs. Contributed by Vinayakumar B.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1575086 13f79535-47bb-0310-9956-ffa450edef68