Fix line spacing in `rndc secroots`
Before this change, there was a missing blank line between the negative trust anchors for one view, and the heading line for the next view. This is because dns_ntatable_totext() omits the last newline. There is an example of the incorrect output below; the fixed output has a blank line before "Start view auth".
secure roots as of 21-Oct-2019 12:03:23.500:
Start view rec
Secure roots:
./RSASHA256/20326 ; managed
Negative trust anchors:
example.com: expiry 21-Oct-2019 13:03:15.000
Start view auth
Secure roots:
./RSASHA256/20326 ; managed
Negative trust anchors:
example.com: expiry 21-Oct-2019 13:03:07.000
Edited by Mark Andrews