Misc. bugfixes. route(8) and netmpls/mpls_rmx.c.

Handling of gateway in rt_addrinfo{} by route(8) and netmpls/mpls_rmx.c
changed. Segements for x-connect are encoded by sockaddr_mpls{} maps to
sockaddr_ftn{}, where in-seg is stored by

 (a) satosmpls(dst)->smpls_label = ...

and out-seg by

 (b) satosftn(dst)->sftn_label = ...

If fec will be removed, call of mpls_link_rtrequest removes all
corrosponding MPLS lanel biding automatically.

Function mpls_rt_setgate deprecated and its codesection merged with
mpls_rt_output_fib.

Misc. bugfixes in netmpls/mpls_arp.c.

Optimized shortcut:

	static __inline void
	mpls_rtalloc_fib(struct mpls_ftn *ftn, u_int fibnum)
	{

		rtalloc_fib((struct route *)ftn, fibnum);
		if (ftn->ftn_ilm != NULL) {
			ftn->ftn_lle = ftn->ftn_lle = /* XXX: <= maps llentry{} */
				NHLFE_SHORTCUT(ftn->ftn_ilm->rt_ifa);
			ftn->ftn_ifa = ftn->ftn_ilm->rt_ifa;
			ftn->ftn_flags = ftn->ftn_ilm->rt_flags;
		}
	}

on LSR llentry{} maps to route{} avoids call of mpls_arpresolve
during i.e. ether_output, if tx host rx ARP_INVREPLY succesfully.