arptables-nft: remove ARPT_INV flags usage

arptables-nft: remove ARPT_INV flags usage

ARPT_ and IPT_INV flags are not interchangeable, e.g.:
define IPT_INV_SRCDEVADDR	0x0080
define ARPT_INV_SRCDEVADDR	0x0010

as these flags can be tested by libarp_foo.so such checks can yield
incorrect results.

Because arptables-nft uses existing code, e.g. xt_mark, it makes
sense to unify this completely by converting the last users of
ARPT_INV_ constants.

Note that arptables-legacy does not do run-time module loading via
dlopen(). Functionaliy implemented by "extensions" in the
arptables-legacy git tree are built-in, so this doesn't break
arptables-legacy binaries.

Fixes: 44457c080590 ("xtables-arp: Don't use ARPT_INV_*")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Phil Sutter <phil@nwl.cc>