[4/4] windowscodecs: Implement IWICComponentFactory::CreateDecoderFromFileHandle.

[Vincent Povirk]

> +    hr = map_file(file, &map, &mem, &size);
> +    if (FAILED(hr)) return hr;
> +
...
> +
> +    hr = IWICStreamImpl_InitializeFromMemory(stream, mem, size.u.LowPart);
> +    if (FAILED(hr)) goto error;

This makes me sad.

Is this really simpler than implementing Write and Seek for a file handle?