HIVE-8496: Re-enable statistics [Spark Branch] (Chao via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633210 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8436: Modify SparkWork to split works with multiple child works [Spark Branch] (Chao via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633268 13f79535-47bb-0310-9956-ffa450edef68
HIVE-7709: Create SparkReporter [Spark Branch] (chengxiang via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633382 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8537: Update to use the stable TaskContext API [Spark Branch] (Chengxiang via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633418 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8540: HivePairFlatMapFunction.java missing license header [Spark Branch] (Chao via Xuefu)

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633473 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8362 - Investigate flaky test parallel.q (Jimmy Xiang via Brock) merged from trunk r1632136

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633507 13f79535-47bb-0310-9956-ffa450edef68
HIVE-8518: Compile time skew join optimization returns duplicated results (Rui via Xuefu) merged from trunk r1633422

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1633508 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'upstream/spark' into spark