CURLOPT_NOBODY(3) on macOS

The text de7bf4ce4cd0, 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.

do the download request without getting the body

CURLOPT_NOBODY(3) on macOS now