tdf#91283 - reset the PrinterController during dispose.

Change-Id: I22c6c534cfefdbb68e965cbd6baab3da3146d9d0

vcl/source/window/printdlg.cxx

@@ -736,6 +736,7 @@ void PrintDialog::dispose()
     mpOKButton.clear();
     mpCancelButton.clear();
     mpHelpButton.clear();
+    maPController.reset();
     ModalDialog::dispose();
 }