SQL OLAP specification error enforcement

Prior to IBM i 7.6, some queries which use both aggregate functions and On-Line Analytical Processing (OLAP) specifications in the same select list did not restrict some incorrect usages. This allowed some invalid queries to run which could result in incorrect results or an error from the query engine. These situations are now correctly diagnosed and issue an SQL error, generally SQLCODE/SQLSTATE -112/42607, -120/42903, or -122/42803.