scrrun: Implement ITextStream Close

[Nikolay Sivov]

>      struct textstream *This = impl_from_ITextStream(iface);
> -    FIXME("(%p): stub\n", This);
> -    return E_NOTIMPL;
> +    HRESULT hr = S_OK;
> +
> +    TRACE("(%p)\n", This);
> +
> +    if(!CloseHandle(This->file))
> +        hr = S_FALSE;
> +
> +    This->file = NULL;
> +
> +    return hr;

This could be right way to do it, but it would be interesting to see 
what happens to other methods behavior when called on closed stream, 
like Read() for example.