svn merge -c 1609401 from trunk for HDFS-6643. Refactor INodeWithAdditionalFields.PermissionStatusFormat and INodeFile.HeaderFormat.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1609402 13f79535-47bb-0310-9956-ffa450edef68