[Bug 43315] Steam fails to start [After update 07/10/2017]

https://bugs.winehq.org/show_bug.cgi?id=43315

--- Comment #6 from Hans Leidekker  ---
(In reply to Kimmo Myllyvirta from comment #1)
> Created attachment 58657 [details]
> quick fix
>
> This is related to WSAIoctl, SIO_GET_EXTENSION_FUNCTION_POINTER. The call is
> successful, but Steam compares if cbBytesReturned < 4, and it fails since
> wine sets it to 0. Not sure how correct the attached patch is, but at least
> Steam starts with it.

Can you please add a test and submit the patch?