bug#14749: rtl.test failure in master

[dsmich]

---- address@hidden wrote: 
> I'm seeing this make check error from rtl.test on master:
> 
> ERROR: rtl.test: load-constant: #\37200 - arguments: ((misc-error #f "~A" 
> ("make-long-immediate unavailable for this target") #f))
> 
> The failing line is:
>     (integer->char 16000)

I did a bisect and it says this started with commit 

e6450062a19bf5d0072d117b69be95c2641c23ab is the first bad commit
commit e6450062a19bf5d0072d117b69be95c2641c23ab
Author: Andy Wingo <address@hidden>
Date:   Sun Jun 16 15:02:34 2013 +0200

    Reduce call-with-values to let for singly-valued producers


-Dale