RxFPC:try to fix RxDBGrid footer row with TSQLQuery

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7476 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/rx/trunk/rxdb/rxdbgrid.pas

@@ -5958,6 +5958,8 @@ begin
   if (not (DatalinkActive and (FGroupItems.Active or FFooterOptions.Active))) or (Columns.Count = 0) or (gsAddingAutoColumns in GridStatus) then
     Exit;
 
+  if Datalink.ActiveRecord < 0 then exit;
+
   if Assigned(OnRxCalcFooterValues)then
   begin
     Inc(FInProcessCalc);