Do not depend on the in-tree filepath library (#478)
Do not depend on the in-tree filepath library (#478)

See #465, #466
snowleopard/shaking-up-ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,snowleopard/hadrian,sdiehl/ghc,bgamari/shaking-up-ghc,sdiehl/ghc,sdiehl/ghc