>ok, how about:
>struct route {
>	struct rtentry *ro_rt;
>	union {
>		struct sockaddr roun_dst_sa;
>		struct sockaddr_storage roun_dst_ss;
>	} ro_un;
>#define	ro_dst		ro_un.roun_dst_sa	/* compatiblity */
>#define	ro_dst_sa	ro_un.roun_dst_ss
>};

	we tried the above already.  it choked sys/netiso (ro_dst is
	used as the name of struct member, and chokes with #define).
	so we'd need to touch sys/netiso anyways even if we use the above.

itojun