GHSA-XVG2-CGV6-6H7V netfoil: Incorrect block responses could lead to localhost traffic

Summary 0.0.0.0 was used instead of NXDOMAIN for block responses. On Linux, which is the target platform for netfoil, the 0.0.0.0 is sent to localhost rather than just dropped. Impact Unintended traffic could be sent to localhost. Impact depends on running services and firewall rules...