libxt_conntrack: properly output negation symbol

Because the wrong flag was checked, the "!" was either wrongly
printed, or not printed at all.
This was broken since v1.4.0-29-ga8ad34c.

Reported-by: Steven Jan Springl <steven@springl.ukfsn.org>
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
1 file changed