Mail: Increase the minimum size of the attachments view.

This restores approximately the old fixed size from before the
previous commit. Ideally this would be the preferred size, not
the minimum size, but that isn't quite possible when contained in
a scroll view.

src/apps/mail/Enclosures.cpp

@@ -331,7 +331,7 @@ BSize
 TListView::MinSize()
 {
 	BSize size = BListView::MinSize();
-	size.height = be_control_look->DefaultLabelSpacing() * 5;
+	size.height = be_control_look->DefaultLabelSpacing() * 11.0f;
 	return size;
 }