HIVE-8677: TPC-DS Q51 : fails with 'init not supported' exception in GenericUDAFStreamingEvaluator.init (Gunther Hagleitner, reviewed by Harish Butani)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1635844 13f79535-47bb-0310-9956-ffa450edef68