Build fail on ghc-7.4

[yihuang]

First, it seems git head version miss this file: Data/TrieMap/ReverseMap/Dual.hs , so i revert to 6cd8c69, then i got this build message:

Data/TrieMap/Representation/TH/ReprMonad.hs:49:9:
    `qClassInstances' is not a (visible) method of class `Quasi'

Data/TrieMap/Representation/TH/ReprMonad.hs:49:49:
    Not in scope: `qClassInstances'

Data/TrieMap/Representation/TH/ReprMonad.hs:82:19:
    Not in scope: data constructor `ClassInstance'

Data/TrieMap/Representation/TH/ReprMonad.hs:82:33:
    `ci_tys' is not a (visible) constructor field name

It seems ghc-7.4's template-haskell have a lot of breaking changes: http://www.haskell.org/ghc/docs/7.4.1/html/users_guide/release-7-4-1.html#id3018738