DERBY-3155: Fix some serialization bugs in the MERGE ConstantActions and add test cases for using trigger transition tables as the source tables of MERGE statements; check in derby-3155-06-aa-triggerTransitionTableAsSource.diff.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1535447 13f79535-47bb-0310-9956-ffa450edef68