[PATCH] ws2_32/tests: Fix compilation warning

[Fabian Maurer]

> It looks initialized to me. What gcc version is that?

gcc version 7.2.0, running on latest Arch Linux. I'm compiling with -Werror, 
that's how I noticed.
Complete error:

> In file included from ../../../../wine-git/include/winsock2.h:47:0,
>                  from ../../../../wine-git/dlls/ws2_32/tests/sock.c:25:
> ../../../../wine-git/dlls/ws2_32/tests/sock.c: In function 
‘SelectReadThread’:
> ../../../../wine-git/include/winsock.h:480:37: error: 
‘readfds.fd_array[__i]’ may be used uninitialized in this function [-
Werror=maybe-uninitialized]
>          if (((cast*)(set))->fd_array[__i]==(fd)) \


Regards,
Fabian Maurer