[TCP]: TCP Low Priority congestion control

[TCP]: TCP Low Priority congestion control

 TCP Low Priority is a distributed algorithm whose goal is to utilize only
 the excess network bandwidth as compared to the ``fair share`` of
 bandwidth as targeted by TCP. Available from:
   http://www.ece.rice.edu/~akuzma/Doc/akuzma/TCP-LP.pdf

Original Author:
 Aleksandar Kuzmanovic <akuzma@northwestern.edu>

See http://www-ece.rice.edu/networks/TCP-LP/ for their implementation.
As of 2.6.13, Linux supports pluggable congestion control algorithms.
Due to the limitation of the API, we take the following changes from
the original TCP-LP implementation:
 o We use newReno in most core CA handling. Only add some checking
   within cong_avoid.
 o Error correcting in remote HZ, therefore remote HZ will be keeped
   on checking and updating.
 o Handling calculation of One-Way-Delay (OWD) within rtt_sample, sicne
   OWD have a similar meaning as RTT. Also correct the buggy formular.
 o Handle reaction for Early Congestion Indication (ECI) within
   pkts_acked, as mentioned within pseudo code.
 o OWD is handled in relative format, where local time stamp will in
   tcp_time_stamp format.

Port from 2.4.19 to 2.6.16 as module by:
 Wong Hoi Sing Edison <hswong3i@gmail.com>
 Hung Hing Lun <hlhung3i@gmail.com>

Signed-off-by: Wong Hoi Sing Edison <hswong3i@gmail.com>
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>