HIVE-5202 : Support for SettableUnionObjectInspector and implement isSettable/hasAllFieldsSettable APIs for all data types. (Hari Sankar via Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1525804 13f79535-47bb-0310-9956-ffa450edef68