DERBY-6351: Syntax error on equal transition table name and correlation name in statement trigger

Change how CreateTriggerNode.bindReferencesClause() checks for the
lack of a correlation name. Instead of checking it indirectly (and
unreliably) by seeing if the table name matches the base table name,
check directly if the correlation name is null.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1526406 13f79535-47bb-0310-9956-ffa450edef68