PIG-3726: Ranking empty records leads to NullPointerException

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1563200 13f79535-47bb-0310-9956-ffa450edef68
PIG-3299: Provide support for LazyOutputFormat to avoid creating empty files

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1563235 13f79535-47bb-0310-9956-ffa450edef68
Revert PIG-3299: Provide support for LazyOutputFormat to avoid creating empty files

git-svn-id: https://svn.apache.org/repos/asf/pig/trunk@1563236 13f79535-47bb-0310-9956-ffa450edef68