PIG-3047: Check the size of a relation before adding it to distributed cache in Replicated join (aniket486)

git-svn-id: https://svn.apache.org/repos/asf/pig/branches/branch-0.12@1536564 13f79535-47bb-0310-9956-ffa450edef68
add missing import statements for PIG-3047 tests

git-svn-id: https://svn.apache.org/repos/asf/pig/branches/branch-0.12@1536593 13f79535-47bb-0310-9956-ffa450edef68