DERBY-3155: Forbid subqueries in the WHEN [ NOT ] MATCHED clauses of MERGE statements; commit derby-3155-19-aa-forbidSubqueriesInMatchedClauses.diff.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1561671 13f79535-47bb-0310-9956-ffa450edef68