HIVE-4838 : Refactor MapJoin HashMap code to improve testability and readability (Brock Noland via Ashutosh Chauhan)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1514760 13f79535-47bb-0310-9956-ffa450edef68
HIVE-4940 udaf_percentile_approx.q is not deterministic (Navis via Brock Noland)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1514771 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-GEN-TESTS-SPLIT-trunk-gd