not every value return in an nlist structure was being

not every value return in an nlist structure was being
coerced to an (off_t) which was only being smashed back down to a (u_long)
as an argument to kvm_read.  If you ask me nl.n_value ought to be a (void *)
but since the type of nl.n_value and the second argument to kvm_read are
the same I got fed up and changed all the off_t's to be that type (u_long).

SCCS-vsn: usr.bin/netstat/if.c 5.18
SCCS-vsn: usr.bin/netstat/inet.c 5.19
SCCS-vsn: usr.bin/netstat/iso.c 5.13
SCCS-vsn: usr.bin/netstat/main.c 5.30
SCCS-vsn: usr.bin/netstat/mbuf.c 5.12
SCCS-vsn: usr.bin/netstat/mroute.c 7.2
SCCS-vsn: usr.bin/netstat/netstat.h 5.4
SCCS-vsn: usr.bin/netstat/ns.c 5.16
SCCS-vsn: usr.bin/netstat/route.c 5.25
SCCS-vsn: usr.bin/netstat/unix.c 5.14