Specify nf_queue max length from userspace

Eric Leblond wrote:
> I did not like the idea of having params split between
two structures.
> And as the user base is still small, I thought we may
break ABI to have
> something cleaner.
> Pablo and you do not like the idea, I wrote a patch
that should not
> break the ABI (attached to the mail).
> In fact, after introducing the new attribute, I just
found it is in a
> way cleaner than my initial one because code does not
depend from a
> structure.

Yes, that is better. I still would prefer to have all
configuration
attributes nested under some common attribute .. but I
can't see a
clean way to do that right now. Let me think about this some
more.