CURLOPT_FTP_USE_EPSV(3) on macOS

The text b9d5ffbcfcf0, as macOS 10.12.5, macOS 10.12.4, macOS 10.12.3, macOS 10.12.2, macOS 10.12.1, macOS 10.12 shipped it.

enable/disable use of EPSV