CURLOPT_ADDRESS_SCOPE(3) on macOS

The text f7ecfa356e36, 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.

set scope for local IPv6 addresses

CURLOPT_ADDRESS_SCOPE(3) on macOS now