merge -c 1442312 from trunk to branch-2 to fix HADOOP-9276. Allow BoundedByteArrayOutputStream to be resettable. Contributed by Arun Murthy

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1442316 13f79535-47bb-0310-9956-ffa450edef68