ForeignPtr-related signatures

[Sven Panne]

Simon Marlow wrote:
> [...] There was this, from Dean Herrington:
>
>   http://haskell.cs.yale.edu/pipermail/ffi/2002-October/000940.html
>
> I don't have any strong feelings (I rarely do, where names are
> concerned).

I would be happy with his proposal. We can leave the IORef stuff in IOExts
as it is and use the new signatures and functions in Data.IORef. The only
annoying thing is the signature of Data.IORef.modifyIORef, but we could
declare the old signature as a bug...  :-]

Cheers,
   S.