4221 on new codegen

[ezyang]

Excerpts from Simon Marlow's message of Fri Feb 04 03:33:11 -0500 2011:
> Yes, I think starting work on the cleanup would be worthwhile at this 
> stage.  It'll be much easier to dig around in the code to find the bugs 
> once all the cruft has gone.

Well, I rolled up my sleeves intending to do the cleanup, and found most of
it had already been done by the "merge in new codegen patch"!  So I guess
I don't have to go do that.

Edward