HADOOP-9124. SortedMapWritable violates contract of Map interface for equals() and hashCode(). (Surenkumar Nihalani via tgraves)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1441575 13f79535-47bb-0310-9956-ffa450edef68