Make fingerprint calculation non-locale dependent.

Signed-off-by: Edward Z. Yang <ezyang@cs.stanford.edu>

Cabal/Distribution/Simple/Configure.hs

@@ -131,7 +131,7 @@ import Control.Exception
 import Control.Monad
     ( liftM, when, unless, foldM, filterM )
 import Distribution.Compat.Binary ( decodeOrFailIO, encode )
-import GHC.Fingerprint ( Fingerprint(..), fingerprintString
+import GHC.Fingerprint ( Fingerprint(..), fingerprintData
 #if __GLASGOW_HASKELL__ >= 710
                        , getFileHash
 #endif
@@ -153,7 +153,7 @@ import Data.Monoid
 import qualified Data.Map as Map
 import Data.Map (Map)
 import Data.Traversable
-    ( mapM )
+    ( mapM, forM )
 import Data.Typeable
 import Data.Char ( chr, isAlphaNum )
 import Numeric ( showIntAtBase, showHex )
@@ -1318,7 +1318,9 @@ computeIPID pkg_descr dep_ipids flagAssignment = do
 #if __GLASGOW_HASKELL__ >= 710
       mapM getFileHash files
 #else
-      mapM (\x -> readFile x >>= (evaluate . fingerprintString)) files
+      forM files $ \f -> do
+        bs <- BS.readFile f
+        BS.useAsCString bs $ \(ptr, len) -> fingerprintData ptr len
 #endif
     -- show is found to be faster than intercalate and then replacement of
     -- special character used in intercalating. We cannot simply hash by