HIVE-2517 : Support group by on struct type (Ashutosh Chauhan via Navis)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1498755 13f79535-47bb-0310-9956-ffa450edef68
HIVE-4436 : hive.exec.parallel=true doesn't work on hadoop-2
 (Gopal V via Navis)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1498773 13f79535-47bb-0310-9956-ffa450edef68