libffi for ARM

[Mike Stump]

On Jul 3, 2007, at 10:02 AM, Daniel Jacobowitz wrote:
> Their declarations force them into particular registers; there's no  
> constraints for the specific registers we need.

I think that it would be reasonable to document that this is an  
appropriate and reasonable thing to do, and it's guaranteed to work,  
if it doesn't already say that...  with that as a feature, I don't  
think we need another feature that does something similar.