HDFS-5675. Add Mkdirs operation to NNThroughputBenchmark. Contributed by Plamen Jeliazkov.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1554071 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch: upstream/trunk