[Cake] Make the dual modes fairer

[Toke Høiland-Jørgensen]

George Amanakis <gamanakis at gmail.com> writes:

> Host fairness does not work well with TCP flows in dual-srchost and
> dual-dsthost setup. The reason is that ACKs generated by TCP flows
> are classified as sparse flows, and affect flow isolation from other
> hosts. Fix this by calculating host_load based only on the bulk flows
> a host generates. In a hash collision the host_bulk_flow_count values must
> be decremented on the old hosts and incremented on the new ones *if* the
> queue is in the bulk set.

Right, thanks! Pushed this to master; go forth and test, everyone! :)

-Toke