Changes to ghc

Changes to ghc:
commit b80d5739361b5879a25de8497ae08dd0bfdbf627
Author: Herbert Valerio Riedel <hvr@gnu.org>
Date:   Sat Jun 21 17:04:32 2014 +0200

    Refactor extension-bitmap in Lexer

    This introduces an Enum type `ExtBits` for the currently used 32 flags
    and introduces a type-synonym `ExtsBitmap` for representing a set over
    `ExtBits`. While at it, the current `Int` was replaced by `Word` to
    have the compiler catch any missed use-sites.

    This will make it easy to swap the `Word`-representation of `ExtsBitmap`
    by something different, such as e.g. a `Word64`

    Test Plan: successful validate

    Differential Revision: https://phabricator.haskell.org/D23