Add support for NTP authentication

[Bernhard Reutner-Fischer]

On 11 October 2018 16:41:13 CEST, Brandon Enochs <enochs.brandon at gmail.com> wrote:
>OK, I added config support to disable NTP authentication and used
>unconditional frees.

hash() and compare_hash() look redundant. Can you use the former to implement the latter?

free_keys could maybe use llist_free() (sp?) if you'd change the keys to be list elts?

And please always provide bloat-o-meter output:
make baseline (with pristine master)
./scripts/bloat-o-meter.py old yours, see make bloat-check (IIRC).

thanks,