svn merge -c 1604011 merging from trunk to branch-2 to fix:HDFS-3848. A Bug in recoverLeaseInternal method of FSNameSystem class. Contributed by Hooman Peiro Sajjad and Chen He.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1604012 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6549. Add support for accessing the NFS gateway from the AIX NFS client. Contributed by Aaron T. Myers.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1604023 13f79535-47bb-0310-9956-ffa450edef68