- only do group prereq on new style distro

- update to 2.17:
* Fix STDERR_SYSLOG log level bug.
* Always close stdout and stderr when daemonizing.
* Implement RFC 7772 Section 5.1.1, 5.1.2, defaulted to on.
* Fixed ExecReload in systemd service file
* Merged ARPHRD_6LOWPAN netlink query from
* Add systemd service file
* Fixed bug in new vs old address list comparison when
responding to netlink messages.
* Fix netlink bug where RADVD reacts to RTM_NEWADDR
messages when there weren't actually any new addresses
to be found. Those RTM_NEWADDR messages were only
* process.c: fixup ugly overflow check
radvd.conf.5.man: minor fixup to 'client' option
radvd.conf.5.man: update abro usage
gram.y: deprecate abro prefix length
device-linux.c: IEEE 802.15.4 musl libc fix
send.c: seconds/miliseconds comparison fix
send.c: preferred lifetime RFC 4862, 5.5.3 fix
defaults.h: remaining lifetime RFC 4862 fix
radvdump: show routes with prefixlen > 64
- run tmpfiles_create in post to ensure creation of rundir
- depend on daemon group to be created before adding user
- fix rundir group permission