HIVE-8893 : Implement whitelist for builtin UDFs to avoid untrused code execution in multiuser mode (Prasad Mujumdar via Szehon)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1640791 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8642 : Hive stack() UDTF Doesn't Support NULL Insert Values (Navis via Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1640798 13f79535-47bb-0310-9956-ffa450edef68