Fix that routed deletes local routes

routed previousely ignored local routes, which have RTF_LOCAL flag, because
such routes have RTF_LLINFO and routed ignored routes having the flag. When
we obsoleted RTF_LLINFO, we removed the ignoring logic from routed, then
routed started removing local routes unexpectedly.

Fix this behavior by teaching local routes to routed to ignore them.

kardel@ reported the issue and helped testing, thanks!

(ozaki-r)