READ and WRITE subscriptions on the same fd

[MediosZ]

In mio, we can do this:

poll.registry().register(
    &mut connection,
    token,
    Interest::READABLE.add(Interest::WRITABLE),
)?;

It creates READ and WRITE subscriptions on the same fd. And this does't work in wasmedge_wasi_socket.

[MediosZ]

I find it's a problem with WASI, so I am closing this.