and fixes the ones that have some.
From https://github.com/xamarin/xamarin-macios/issues/9724
We do not _normally_ add availability attributes on enums **members** that represent error codes. In part because it's a lot of metadata and, foremost, because it's not really helpful to write code. E.g.
```csharp
var err = Call.Api (1);
switch (err) {
case NSError.Bad:
case NSError.Wrong:
Console.WriteLine ($"API failed: {err});
break;
case NSError.Ok:
break;
default:
Console.WriteLine ($"Unknown error code {err}");
break;
}
```
Adding version checks inside this would be complicated (source wise) and not really helpful since
* API can return undefined error code (and the error logic should work);
* Availability information is not 100% accurate;
As such we default to not add them - but we some time forgot about it.
Sebastien Pouliot