RSSA backend

[Stephen Weeks]

> Why am I plagued with inexplicable regression errors?  I can't reproduce
> these either locally or on the machine where the rest of the regressions
> are still going (i.e., over on that machine, I'm using exactly the same
> executable and regression files that yielded the above).
> 
> Alright, it only seems to crop up when running in the regression script.

I just checked out the main trunk and used an NJ compiled G0 to run
the regression script on {array,callcc,fft,filesys,world1} without
problems, on all three of our linux machines here.  I have no idea
what's going on.