Improve chooseProtocol logging (#873)
Improve chooseProtocol logging (#873)

Add `target` and `ip_protocol` fields to the logging in teh
`chooseProtocol()` utility function. This makes debugging output easier.

Signed-off-by: SuperQ <9bbf917dc63fbaa40c67921332d26cf16a50db75@gmail.com>
prometheus/blackbox_exporter