Increase dependent cabal version to avoid the bug of cabal

According to https://github.com/haskell/cabal/issues/1045, test suites
don't contribute to cabal_macros.h MIN_VERSION_pkg pragmas in the prev
ious version of cabal. This bug is fixed in cabal 1.16. However, haske
ll-platform 2012.4.0 comes with cabal 1.14