[1/5] resend include: bring in6_addr into line with the MS definition

[Jeff Latimer]

Rob Shearman wrote:
> This looks right, but in recent PSDKs it has moved from ws2tcpip.h to 
> in6addr.h.
Thanks, I knew that the latest PSDK had split this out but as none of 
the PSDK other changes had been worked into the tree, I was reluctant 
and unsure of whether that PSDK should be used.  I have resubmitted the 
set with in6addr.h.