convert interfaces to sockaddr's and add hooks for routing

convert interfaces to sockaddr's and add hooks for routing

SCCS-vsn: sys/net/if.c 4.11
SCCS-vsn: sys/net/if.h 4.11
SCCS-vsn: sys/vax/if/if_dmc.c 4.7
SCCS-vsn: sys/vax/if/if_en.c 4.44
SCCS-vsn: sys/deprecated/netimp/if_imp.c 4.20
SCCS-vsn: sys/net/if_loop.c 4.8
SCCS-vsn: sys/vax/if/if_uba.c 4.10
SCCS-vsn: sys/netinet/in_pcb.c 4.22
SCCS-vsn: sys/netinet/ip_input.c 1.35
SCCS-vsn: sys/netinet/ip_output.c 1.27
SCCS-vsn: sys/net/raw_cb.c 4.6
SCCS-vsn: sys/deprecated/netimp/raw_imp.c 4.9
SCCS-vsn: sys/netinet/raw_ip.c 4.9
SCCS-vsn: sys/deprecated/netpup/raw_pup.c 4.9
SCCS-vsn: sys/net/route.c 4.2
SCCS-vsn: sys/net/route.h 4.2
SCCS-vsn: sys/netinet/tcp_output.c 4.36
SCCS-vsn: sys/netinet/tcp_subr.c 4.20
SCCS-vsn: sys/netinet/udp_usrreq.c 4.23