windows: add WSADuplicateSocket

WSADuplicateSocket is useful to pass sockets between processes on
Windows.

For golang/go#10350.

Change-Id: I6563184fe4d4477d402a6af81b254bd8aa992d2e
Reviewed-on: https://go-review.googlesource.com/c/sys/+/668215
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Carlos Amedee <carlos@golang.org>

Author: qmuntal

windows/syscall_windows.go

@@ -870,6 +870,7 @@ const socket_error = uintptr(^uint32(0))
 //sys	WSARecvFrom(s Handle, bufs *WSABuf, bufcnt uint32, recvd *uint32, flags *uint32,  from *RawSockaddrAny, fromlen *int32, overlapped *Overlapped, croutine *byte) (err error) [failretval==socket_error] = ws2_32.WSARecvFrom
 //sys	WSASendTo(s Handle, bufs *WSABuf, bufcnt uint32, sent *uint32, flags uint32, to *RawSockaddrAny, tolen int32,  overlapped *Overlapped, croutine *byte) (err error) [failretval==socket_error] = ws2_32.WSASendTo
 //sys	WSASocket(af int32, typ int32, protocol int32, protoInfo *WSAProtocolInfo, group uint32, flags uint32) (handle Handle, err error) [failretval==InvalidHandle] = ws2_32.WSASocketW
+//sys	WSADuplicateSocket(s Handle, processID uint32, info *WSAProtocolInfo) (err error) [failretval!=0] = ws2_32.WSADuplicateSocketW
 //sys	GetHostByName(name string) (h *Hostent, err error) [failretval==nil] = ws2_32.gethostbyname
 //sys	GetServByName(name string, proto string) (s *Servent, err error) [failretval==nil] = ws2_32.getservbyname
 //sys	Ntohs(netshort uint16) (u uint16) = ws2_32.ntohs