HsExpr: Ensure Type is derived on ThModFinalizers
HsExpr: Ensure Type is derived on ThModFinalizers

This is necessary to bootstrap with GHC 7.8.

GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc,GaloisInc/halvm-ghc