HDFS-6492. Support create-time xattrs and atomically setting multiple xattrs. (wang)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1603978 13f79535-47bb-0310-9956-ffa450edef68
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.

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HDFS-6549. Add support for accessing the NFS gateway from the AIX NFS client. Contributed by Aaron T. Myers.


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