suppress: add track by_either mode

suppress: add track by_either mode

So far suppress rules would apply to src or dst addresses of a packet.
This meant that if a ip would need to suppressed both as src and as dst,
2 suppress rules would be needed.

This patch introduces track by_either, which means that the ip(s) in the
suppress rule are tested against both the packets source and dest ip's.
If either of them is on the suppress list, the alert is suppressed.