libpfctl: migrate to DIOCGETSTATESV2

[kp]

Summary

Stop using the *NV version to retrieve states, as its performance is
unacceptably bad.

MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")

[mjg]

Commit message should include perf numbers.

[mjg]

lib/libpfctl/libpfctl.c

716–718

version check should be performed here -- if lower than PF_STATE_VERSION then error out

[mjg]

lib/libpfctl/libpfctl.c

716–718

alternatively you can extend the request struct to include version number you expect, then the kernel can tell if you if it supports it to begin with

[mjg]

lib/libpfctl/libpfctl.c

716–718

now that I wrote it that's way better, in particular it can reduce the spare set -- worst case, should the struct run out of spares, a dedicated export func can be created to accomodate older userspace

[kp]

Tell the kernel what version we expect

[mjg]

lib/libpfctl/libpfctl.c

702

this should bzero for consistency with code below