[distcc] please try distcc head's new scheduler

[Martin Pool]

After some good suggestions from Rusty I think the 1.2cvs scheduler is
now fixed.  My measurements show it's no slower and perhaps a little
faster than in 1.1 for fast networks, and it should be better for slow
ones. 

I can't test every situation though, so please download it and try for
yourself.  Back-to-back measurements against 1.1 would be particularly
good.

This adds an experimental syntax for setting a maximum number of tasks
for each server:

  DISTCC_HOSTS='localhost/2 superego/16'

-- 
Martin