nflog: introduce mnl API v2

[glongo]

Make sure these boxes are signed before submitting your Pull Request -- thank you.

• I have read the contributing guide lines at https://redmine.openinfosecfoundation.org/projects/suricata/wiki/Contributing
• I have signed the Open Information Security Foundation contribution agreement at https://suricata-ids.org/about/contribution-agreement/
• I have updated the user guide (in doc/userguide/) to reflect the changes made (if applicable)

Link to redmine ticket:
https://redmine.openinfosecfoundation.org/issues/3383

Describe changes:
If libmnl is present on the system, nflog will use the new api otherwise it still relies on the old ones.

PRScript output (if applicable):

• PR glongo: https://buildbot.openinfosecfoundation.org/builders/glongo/builds/229
• PR glongo-pcap: https://buildbot.openinfosecfoundation.org/builders/glongo-pcap/builds/93

#suricata-verify-pr:
#suricata-verify-repo:
#suricata-verify-branch:
#suricata-update-pr:
#suricata-update-repo:
#suricata-update-branch:
#libhtp-pr:
#libhtp-repo:
#libhtp-branch:

[victorjulien]

Thanks Giuseppe. What is the advantage of using libmnl?

[victorjulien]

Thanks Giuseppe. What is the advantage of using libmnl?

@glongo any feedback on this?

[glongo]

Libnfnetlink is deprecated and it's suggested to migrate to libmnl, which is the netlink library used in nftables.

I think it should slightly bring better performance to nflog given its semplicity in handling netlink sockets, but I haven't made any performance tests to confirm that.

If you find these changes interesting, I can rework the patchset and send a new PR.

[1] https://lore.kernel.org/netdev/YkxUru2QG%2Fo1BlTV@orbyte.nwl.cc/T/