curl_easy_setopt(3) on macOS

The text 381f2e417d3e, as Mac OS X 10.7.5, Mac OS X 10.7.4, Mac OS X 10.7.3, Mac OS X 10.7.2, Mac OS X 10.7.1, Mac OS X 10.7 shipped it.

set options for a curl easy handle

curl_easy_setopt(3) on macOS now