QFileDialog: Only focus file name edit when becoming visible

Doing it when hiding the dialog (which happens when closing it) makes no
sense, and messes with the focus object for no reason.

Change-Id: I4831d4a9b3c22248594f52bfa3b14dc73db110b7
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

src/widgets/dialogs/qfiledialog.cpp

@@ -860,7 +860,7 @@ void QFileDialog::setVisible(bool visible)
         }
     }
 
-    if (d->usingWidgets())
+    if (visible && d->usingWidgets())
         d->qFileDialogUi->fileNameEdit->setFocus();
 
     QDialog::setVisible(visible);