CURLOPT_INTERFACE(3) on macOS

The text 0a25f2706496, 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.

source interface for outgoing traffic

CURLOPT_INTERFACE(3) on macOS now