HIVE-8535: Enable compile time skew join optimization for spark [Spark Branch] (Rui via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1635180 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8617: Turn on all join .q tests #2 [Spark Branch] (Chao via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1635272 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8616: convert joinOp to MapJoinOp and generate MapWorks only [Spark Branch] (Suhas via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1635361 13f79535-47bb-0310-9956-ffa450edef68