HIVE-784 : Support uncorrelated subqueries in the WHERE clause (Harish Butani via Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1535040 13f79535-47bb-0310-9956-ffa450edef68

Conflicts:

	ql/src/java/org/apache/hadoop/hive/ql/ErrorMsg.java
	ql/src/java/org/apache/hadoop/hive/ql/parse/HiveParser.g
	ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java