addForeignPtrFinalizer

[Simon Marlow]

> > I tell you what, I'll implement finalizer ordering if you 
> guys implement
> > full Haskell finalizers :-)
> 
> How about providing newForeignPtr as specified?  (Or are you 
> still hoping?)

Still hoping ;-)  The discussion seemed to stop without reaching a
conclusion last time.  At least, I still don't think I fully understand
why the current newForeignPtr is not implementable without concurrency,
given that a form of context switching must already exist in order to
implement foreign import that re-enters Haskell.

Anyway, it's not that big a deal.  I'll hopefully get round to making
the change soon.

Cheers,
	Simon