bootstrap comparison failure on alpha

[Brad Lucier]

> It appears that this problem doesn't have anything to do with my GC
> changes -- I backed them out, and still get comparison failures on
> IRIX.
> 
> I'm going to use that massively parallel IRIX box to try the binary
> search thing to see what first caused the failure...

No need, I believe it was the recent changes to the loop code; things
bootstrap OK now on alpha.

I apologize for sending you e-mail about this directly; I guess after
your backing out the recent GC change fixed the problem on Solaris,
I thought that the other changes might have had something to do with
the problem on Alpha linux.

Brad