Proposal: Make Permissions type abstract

[Yitzchak Gale]

Ian Lynagh wrote:
> Proposal: Make Permissions type abstract
> Ticket: http://hackage.haskell.org/trac/ghc/ticket/4149

+1.

It is possible that this will still break some packages.
Do we know how many packages, and which, are potentially
affected?

In any case that is good to know, and we should make sure
all maintainers know about this proposal. More breakage
may ensue as the platform-dependent APIs begin to diverge.

Thanks,
Yitz