This patch makes selection of congestion control algorithm simpler by 
using a single sysctl for that purpose, rather than a cascade of sysctls.

The patch also does some minor cleanups to avoid cascade actions between
algorithms so that flow control is cleaner.

Possible improvements:
  - Use a string when reading/writing from sysctl to make it more
    friendly to humans.
  - And/Or, provide a list of all available congestion control
    algorithms.

The patch is against 2.6.11-rc4-bk9.

Signed-Off-By: Yee-Ting Li <yee-ting.li@nuim.ie>
Signed-Off-By: Baruch Even <baruch@ev-en.org>