DERBY-6212: NullPointerException when calling a procedure with sub-query as argument

Raise a syntax error instead of a NullPointerException if a sub-query
is given as argument to a CALL statement.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1480909 13f79535-47bb-0310-9956-ffa450edef68