curl_formadd(3) on macOS

The text 2483d56d9186, as Mac OS X 10.6.8, Mac OS X 10.6.7, Mac OS X 10.6.6, Mac OS X 10.6.5, Mac OS X 10.6.4, Mac OS X 10.6.3 shipped it.

add a section to a multipart/formdata HTTP POST

curl_formadd(3) on macOS now