Use rtfree(9) instead of decrementing rt_refcnt in rt_getifa().
Use rtfree(9) instead of decrementing rt_refcnt in rt_getifa().

Note that it is safe to keep a reference to the ifa pointed by a route
entry after freeing the entry iff the ifa is valid.

ok bluhm@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars