TCustomBufDataset: set PacketRecords to 1 only on a UniDirectional dataset

git-svn-id: trunk@44633 -
(cherry picked from commit e08d8bba82aaa9ce9e00fdb4eaff6e7d65c12e45)

packages/fcl-db/src/base/bufdataset.pas

@@ -2013,7 +2013,8 @@ begin
     begin
     SetUniDirectional(AValue);
     ClearIndexes;
-    FPacketRecords := 1; // temporary
+    if IsUniDirectional then
+      FPacketRecords := 1; // UniDirectional dataset does not allow FPacketRecords<0
     end;
 end;