[PATCH wayland] Add "enum" attribute to "arg" elements

[Bill Spitzak]

Since all the codegen packages that want to use this enum attribute have 
not been written yet I don't think back-compatibility is an issue. They 
are not using uint because they do not exist yet!

The C codegen can continue to ignore the enum, or use it in a way that 
does not break code that tries to pass an integer or the wrong enum.

On 04/24/2015 12:07 AM, Pekka Paalanen wrote:

> The purpose of docenum was purely for documentation. An API generator
> must ignore all docenum annotations. This was the backward-compatible
> addition.
>
> Any attribute that modifies the generated API in incompatible ways
> cannot be added after the interface has been released as stable. If
> your function argument was uint, and you change it to an enum in a
> strictly typed language, does it not have a good chance of breaking
> someone's build?