Access2Base - PATCH-01 Field.setValue

Gives erroneously an  error message when argument is Null and field is nullable
https://forum.openoffice.org/en/forum/viewtopic.php?f=47&t=61447&sid=48e231a12084933d9da1b47e50b186ea#p323714

Change-Id: I37be06e5c30f1294756d28ba88d903f9fa28d8bb
Reviewed-on: https://gerrit.libreoffice.org/11198
Reviewed-by: Jean-Pierre Ledure <jp@ledure.be>
Tested-by: Jean-Pierre Ledure <jp@ledure.be>