[current tinderbox] failure on powerpc/powerpc

[Peter Grehan]

> While I suppose it might be possible to drop the #if completely, it
> would be better to use #if CHAR_MIN == 0 here.  That would make it work
> for FreeBSD/arm too, as well as any platform where chars are unsigned by
> default on which this code may run.

  Sure - it's not my code so I just did the quickest hack I could to get 
it compiling.

later,

Peter.