nd6_free(): If the reason for the deletion is just garbage collection, and the neighbor is an active default router, do not delete it.  Instead, reset the GC timer using the router's lifetime.  Simply deleting the entry would affect default address selection, which is not necessarily a good thing, especially when we're using router preference values.
nd6_free():
If the reason for the deletion is just garbage collection, and the
neighbor is an active default router, do not delete it.  Instead,
reset the GC timer using the router's lifetime.  Simply deleting the
entry would affect default address selection, which is not necessarily
a good thing, especially when we're using router preference values.

MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame