Since the radvd daemon drops privileges when starting, and
it doesn't write its pidfile until *after* dropping privs,
it is unable to do so if /var/run/radvd does not already
exist with daemon:daemon ownership. Even if this directory
is created during packaging, there's no guarantee that it
will persist, as /var/run on tmpfs is quite common these
days (as that's how this problem was discovered here).
Signed-off-by: Robby Workman <rworkman@slackbuilds.org>