Add findModuleFiles and export it.
Add findModuleFiles and export it.

See #210.

snowleopard/hadrian,bgamari/shaking-up-ghc,sdiehl/ghc,snowleopard/shaking-up-ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,sdiehl/ghc,izgzhen/hadrian,sdiehl/ghc,sdiehl/ghc