curl_easy_setopt(3) on macOS

The text 8a0fc2d5495f, as Mac OS X 10.8.5, Mac OS X 10.8.4, Mac OS X 10.8.3, Mac OS X 10.8.2, Mac OS X 10.8.1, Mac OS X 10.8 shipped it.

set options for a curl easy handle

curl_easy_setopt(3) on macOS now