Revert "Fix tests for Cabal <= 1.16"

The problem the reverted commit tried to fix seems to have been just a
symptom of another root cause that was later fixed as the problem does
not seem to occur anymore even without this changeset also this
changeset broke cabal sandboxes with ghc < 7.8.

Fix #262

This reverts commit 8741323f5b.

Conflicts:
	Language/Haskell/GhcMod/GhcPkg.hs

test/CradleSpec.hs

@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 module CradleSpec where
 
 import Control.Applicative
@@ -32,11 +31,7 @@ spec = do
                     cradleCurrentDir = "test" </> "data" </> "subdir1" </> "subdir2"
                   , cradleRootDir    = "test" </> "data"
                   , cradleCabalFile  = Just ("test" </> "data" </> "cabalapi.cabal")
-#if MIN_VERSION_Cabal(1,18,0)
                   , cradlePkgDbStack = [GlobalDb, PackageDb (cwd </> "test/data/.cabal-sandbox/i386-osx-ghc-7.6.3-packages.conf.d")]
-#else
-                  , cradlePkgDbStack = [GlobalDb, UserDb]
-#endif
                   }
         it "works even if a sandbox config file is broken" $ do
             withDirectory "test/data/broken-sandbox" $ \dir -> do