ftp: active conn, place calling sockopt callback at the end of function

Commit b91d29a28e170c16d65d956db79f2cd3a82372d2 introduces a bug and breaks Curl_closesocket function. sock_accepted flag for the second socket should be tagged as TRUE before the sockopt callback is called because in case the callback returns an error, Curl_closesocket function is going to call the - fclosesocket - callback for the accept()ed socket