Changes:

NHLFE is encoded by mpls_rt{}, but accessed via ifaddr{}:

 	<ifa_addr, ifa_dstaddr> := <<LSP In, MPLS Op>, LSP Out>

 o ifa_addr denotes search key and MPLS Operation
 o ifa_dstaddr denotes next hop

	struct sockaddr_mpls {
		uint8_t	smpls_len;
		sa_family_t	smpls_family;
		uint16_t	smpls_index;
		uint32_t	smpls_label;		<- search key or LSP out
		uint32_t	smpls_reserved;
		uint32_t	smpls_operation;	<- MPLS operation
	};

Signature changed:
 o mpls_shim_push()
 o mpls_swap()

 1st arg denotes MPI
 2nd arg denotes sockaddr{}