HIVE-6434 : Restrict function create/drop to admin roles (Jason Dere via Thejas Nair)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1577424 13f79535-47bb-0310-9956-ffa450edef68
HIVE-6567 : "show grant ... on all" fails with NPE (Thejas Nair, reviewed by Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1577428 13f79535-47bb-0310-9956-ffa450edef68