Fix DB2 10 test issues

Author: beikov

hibernate-core/src/main/java/org/hibernate/query/sqm/mutation/internal/cte/CteInsertHandler.java

@@ -1141,7 +1141,7 @@ private void handleConflictClause(
 					final List<ColumnReference> assignmentColumns = new ArrayList<>( assignments.size() );
 					final QuerySpec updateSubquery = new QuerySpec( false, 1 );
 					for ( Assignment assignment : assignments ) {
-						assignmentColumns.add( (ColumnReference) assignment.getAssignable() );
+						assignmentColumns.addAll( assignment.getAssignable().getColumnReferences() );
 						updateSubquery.getSelectClause().addSqlSelection(
 								new SqlSelectionImpl( assignment.getAssignedValue() )
 						);

hibernate-core/src/test/java/org/hibernate/orm/test/query/criteria/CriteriaWindowFunctionTest.java

@@ -255,7 +255,7 @@ public void testRank(SessionFactoryScope scope) {
 	}
 
 	@Test
-	@SkipForDialect(dialectClass = DB2Dialect.class, majorVersion = 10, reason = "No support for percent_rank and cume_dist functions")
+	@SkipForDialect(dialectClass = DB2Dialect.class, majorVersion = 10, reason = "No support for percent_rank and cume_dist functions before DB2 11")
 	@SkipForDialect(dialectClass = AltibaseDialect.class, reason = "No support for percent_rank and cume_dist functions with over clause")
 	public void testReusableWindow(SessionFactoryScope scope) {
 		scope.inTransaction(