Building system again

[Roman Leshchinskiy]

Simon Peyton-Jones wrote:
> 
> The current plan is to have a "last good build" snapshot Darcs repo.  If you pull from that, you'll know that Buildbot managed to build from start to finish without problems.

FWIW, none of the problems I've encountered would have been caught by 
BuildBot, I think. The darcs-all thing only applies to branches; the 
haddock thing only to packages for which haddock fails; and I assume 
BuildBot doesn't do make clean or make -j.

Roman