Unbreak library stripping with GHCJS.
Unbreak library stripping with GHCJS.

Fixes #3330 (according to
https://github.com/haskell/cabal/pull/3339#issuecomment-210098437).

Heather/cabal,thomie/cabal,bennofs/cabal,sopvop/cabal,headprogrammingczar/cabal,kolmodin/cabal,bennofs/cabal,headprogrammingczar/cabal,Heather/cabal,gbaz/cabal,sopvop/cabal,sopvop/cabal,themoritz/cabal,mydaum/cabal,thomie/cabal,themoritz/cabal,kolmodin/cabal,mydaum/cabal,themoritz/cabal,gbaz/cabal