add Cabal description for GF

src-3.0/GF/Compile/GetGrammar.hs

@@ -35,7 +35,7 @@ import Data.Char (toUpper)
 import Data.List (nub)
 import qualified Data.ByteString.Char8 as BS
 import Control.Monad (foldM)
-import System (system)
+import System.Cmd (system)
 
 getSourceModule :: Options -> FilePath -> IOE SourceModule
 getSourceModule opts file0 = do

src-3.0/GF/Compile/ReadFiles.hs

@@ -34,7 +34,6 @@ import Data.Char
 import Data.List
 import qualified Data.ByteString.Char8 as BS
 import qualified Data.Map as Map
-import System
 import System.Time
 import System.Directory
 import System.FilePath