DFSInputStream#ReaderStrategy family don't look very good. This refactors a little bit to make them make more sense.
test_libhdfs_threaded_hdfs_static and test_libhdfs_zerocopy_hdfs_static are failing
ReadStatistics not thread safe when hedged read is enabled
Actual read size of open file in encryption zone still larger than listing size even after enabling HDFS-11402 in Hadoop 2