kernel: switch openwrt default to TCP cubic from westwood (patch by Dave Täht)

kernel: switch openwrt default to TCP cubic from westwood (patch by Dave Täht)

Despite Westwood's theoretical advantages, in nearly
every benchmark we ran last year, TCP cubic won, whether it be
on correct RTT estimates, amount of buffering, responsiveness,
etc. on current hardware and software designs.

(both need timestamps on to work well, besides)

TCP cubic is better maintained and understood than westwood,
also.

While a scenario where westwood would win possibly exists,
there is too much buffering in the wifi stack in particular
at present, to see any improvement.

If you wish to exercise various TCPs under contention,
the current svn head of netperf (2.6) has options to switch
congestion control agorithms on the fly, as does iperf.

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@32514 3c298f89-4303-0410-b956-a3cf2f4a3e73