Instead of setting the rdnss address directly, this change adds a LINKLOCAL keyword so the address will be dynamically deducted from the specified interface.
With this change it is possible to switch hardware or ethernet interfaces without changing the rtadvd.config while using the rdnss feature.
Setting the address manually is, of course, still possible.
rtadvd.config example:
denis@host ~ % more rtadvd.conf
em0::rdnss="LINKLOCAL":
em1::rdnss="LINKLOCAL":
em2::rdnss="fe80::1d04:3630:60c3:1ade":