discouraging register use

[DJ Delorie]

> > Apparently, if reloading is needed, ONE alternative is chosen, and
> > reload tries to make it work.  If it fails, there doesn't seem to be a
> > mechanism for trying other alternatives to see if they work.  Am I
> > reading this right?
> 
> Yes.  Thus hackery with PREFERRED_RELOAD_CLASS and such.

Could you elaborate on what kind of hackery would help?  I'm sure I've
added lots of arbitrary hackery so far, but IIRC P_R_C should only
reduce the class, not expand it to include other things.