message: Allow deprecated in the implement_vertex macro
  This is called by users and fires the deprecation warning
  in user code.
diff: @@ -109,6 +109,7 @@ macro_rules! implement_vertex {
  Cow::Borrowed(stringify!($field_name)),
  {
  // calculate the offset of the struct fields
  + #[allow(deprecated)]
  let dummy: $struct_name = unsafe { ::std::mem::uninitialized() };
  let offset: usize = {
  let dummy_ref = &dummy;
  