update extra-source-paths, CF ucsd-progsys/liquid-fixpoint#339
update extra-source-paths, CF ucsd-progsys/liquid-fixpoint#339

ucsd-progsys/liquidhaskell,ucsd-progsys/liquidhaskell,ucsd-progsys/liquidhaskell,ucsd-progsys/liquidhaskell,ucsd-progsys/liquidhaskell,ucsd-progsys/liquidhaskell