Synchronet now requires the libarchive development package (e.g. libarchive-dev on Debian-based Linux distros, libarchive.org for more info) to build successfully.

Optimize the newsgroup list part of previous commit.

Don't regenerate the newsgroup_list for *every* authenticated NNTP command.
3 jobs for query_pr in 14 minutes and 25 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #1684
build-sbbs

00:12:17

passed #1685
build-sexpots

00:00:13

passed #1686
build-syncterm

00:01:53