Fix use-after-close lazy IO bug
Fix use-after-close lazy IO bug

Make `getPrologue` force `parseParas dflags str` before returning. Without this,
it will attempt to read from the file after it is closed, with unspecified and
generally bad results.

Signed-off-by: David Feuer <45974cab5fc33d9f0d3677077385ac4f89cda35f@gmail.com>
Signed-off-by: Edward Z. Yang <dbd597f5635f432486c5d365e9bb585b3eaa1853@cs.stanford.edu>

niteria/haddock,Helkafen/haddock,idontgetoutmuch/haddock,Fuuzetsu/haddock,niteria/haddock,haskell/haddock,haskell/haddock,Fuuzetsu/haddock,haskell/haddock,haskell/haddock,randen/haddock,Helkafen/haddock,idontgetoutmuch/haddock,Helkafen/haddock,mrBliss/haddock,randen/haddock,haskell/haddock,mrBliss/haddock,idontgetoutmuch/haddock,niteria/haddock,Fuuzetsu/haddock,randen/haddock,Fuuzetsu/haddock,mrBliss/haddock