[Cake] CAKE upstreaming - testers wanted, ACK filtering rescuers needed

[Toke Høiland-Jørgensen]

For those who have not been following the discussion on the upstreaming
patches, here's an update:

- I've just pushed patches to only split GSO packets when shaping below
  one gigabit; and hopefully made the overhead compensation code deal
  gracefully with GSO packets if someone for some reason wants to use
  the shaper at speeds higher than that and still use the overhead
  compensation code.

- It turns out that the ACK filtering code does not properly sanity
  check the packet sizes, and so can potentially crash the box running
  CAKE if it receives malformed packets. So if no one steps up to fix
  that within the next few days, or I'll submit the next version without
  it (I'm not going to open that particular can of worms)... This
  doesn't mean it can't be added back later, of course, it just means it
  won't go upstream this time around.

- NAT mode is now enabled by default; doesn't seem to be a good reason
  not to as the compile time dependency already makes the module depend
  on conntrack.


So please do test the current git version (cobalt branch, still). I'm
planning to resubmit on Friday.

-Toke