CURLOPT_MAX_SEND_SPEED_LARGE(3) on macOS

The text 12761b6a7330, as macOS 10.12.5, macOS 10.12.4, macOS 10.12.3, macOS 10.12.2 shipped it.

rate limit data upload speed

CURLOPT_MAX_SEND_SPEED_LARGE(3) on macOS now