DERBY-590: Change the special NO_CEILING value from 0 to NULL for the scoreCeiling argument to the Lucene query table function; commit derby-590-30-aa-nullableScoreCeiling.diff.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1593701 13f79535-47bb-0310-9956-ffa450edef68