HIVE-7395: Work around non availability of stats for partition columns (Laljo John Pullokkaran via Gunther Hagleitner)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/cbo@1610477 13f79535-47bb-0310-9956-ffa450edef68
HIVE-7407: Handle UDFs generically (Laljo John Pullokkaran via Gunther Hagleitner)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/cbo@1610594 13f79535-47bb-0310-9956-ffa450edef68