HIVE-7744 In Windowing Streaming mode Avg and Sum give incorrect results when Wdw size is same as partition size (Harish Butani via Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1618481 13f79535-47bb-0310-9956-ffa450edef68