Pull up following revision(s) (requested by rmind in ticket #985):
	sys/net/npf/npf_impl.h: revision 1.35
	sys/net/npf/npf_nat.c: revision 1.21
	sys/net/npf/npf_session.c: revision 1.26
npf_session_setnat: fix the race condition when the old connection is still
being expired while a new/duplicate is being created.
Apply patch, requested by rmind in ticket 986:
	usr.sbin/npf/npfctl/npf_ncgen.c			patch
	sys/net/npf/npf_instr.c				patch
fix the byteorder for port range comparison
tickets 985 and 986