HIVE-6258 : sql std auth - disallow cycles between roles (Thejas Nair, reviewed by Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1563453 13f79535-47bb-0310-9956-ffa450edef68
HIVE-6334 : sql std auth - pass username from sessionstate to v2 authorization interface (Thejas Nair, reviewed by Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1563472 13f79535-47bb-0310-9956-ffa450edef68