system/iptables: avoid trap when run "iptables -L" if configured CONF…

[masc2008]

avoid trap when run "iptables -L" if configured CONFIG_NET_NAT while not configured CONFIG_NET_IPFILTER
It's a trap happen everytime.

It's a trap happen everytime.

it can fix issue: #3294

[masc2008]

[BUG] trap when run "iptables -L" if configured CONFIG_NET_NAT while not configure CONFIG_NET_IPFILTER #3294 #3294

[xiaoxiang781216]

@masc2008 please fix:

../nuttx/tools/checkpatch.sh -c -u -m -g 85539a1223c4770ee36e68817f5bfe91e6b49369..HEAD
❌ Commit subject too long > 80
❌ Missing Signed-off-by
Used config files:
    1: .codespellrc
Some checks failed. For contributing guidelines, see:

[masc2008]

updated the commit info, please further review.

[cederom]

Still codespell needs a fix :-)

[masc2008]

sorry, but I didn't realize which typo should be fixed. while I updated the comments first. thanks!

[xiaoxiang781216]

sorry, but I didn't realize which typo should be fixed. while I updated the comments first. thanks!

git commit -s --amend to add signoff to the commit message, @masc2008

[masc2008]

thanks, I thought the "Signed-off-by" info will be added automatically when it was merged.

[cederom]

Thank you @masc2008 :-) Let's just make sure CI builds fine this time :-)