HADOOP-8815. RandomDatum needs to override hashCode(). Contributed by Brandon Li.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1389661 13f79535-47bb-0310-9956-ffa450edef68

Conflicts:
	hadoop-common-project/hadoop-common/CHANGES.txt

(cherry picked from commit 3ede27f4557c9e90430a7a3f385b8be243e89688)

Conflicts:
	hadoop-common-project/hadoop-common/CHANGES.txt
HDFS-6134 and HADOOP-10150 subtasks.
Fix up CHANGES.txt for HDFS-6134, HADOOP-10150 and related JIRAs following merge to branch-2

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
	hadoop-mapreduce-project/CHANGES.txt

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt