cf-socket: turn off IPV6_V6ONLY on Windows if it is supported by lifenjoiner · Pull Request #10975 · curl/curl

It makes support for IPv4-mapped IPv6 addresses. IPV6_V6ONLY refs: https://en.wikipedia.org/wiki/IPv6#IPv4-mapped_IPv6_addresses https://github.com/golang/go/blob/master/src/net/ipsock_posix.go htt...