RawFilePath conversion of System.Directory

By using System.Directory.OsPath, which takes and returns OsString,
which is a ShortByteString. So, things like dirContents currently have the
overhead of copying that to a ByteString, but that should be less than
the overhead of using Strings which often in turn were converted to
RawFilePaths.

Added Utility.OsString and the OsString build flag. That flag is turned
on in the stack.yaml, and will be turned on automatically by cabal when
built with new enough libraries. The stack.yaml change is a bit ugly,
and that could be reverted for now if it causes any problems.

Note that Utility.OsString.toOsString on windows is avoiding only a
check of encoding that is documented as being unlikely to fail. I don't
think it can fail in git-annex; if it could, git-annex didn't contain
such an encoding check before, so at worst that should be a wash.

CmdLine/GitRemoteAnnex.hs

@@ -57,6 +57,7 @@ import Utility.Tmp.Dir
 import Utility.Env
 import Utility.Metered
 import Utility.FileMode
+import qualified Utility.RawFilePath as R
 
 import Network.URI
 import Data.Either
@@ -65,7 +66,6 @@ import qualified Data.ByteString as B
 import qualified Data.ByteString.Char8 as B8
 import qualified Data.Map.Strict as M
 import qualified System.FilePath.ByteString as P
-import qualified Utility.RawFilePath as R
 import qualified Data.Set as S
 
 run :: [String] -> IO ()
@@ -1162,7 +1162,8 @@ specialRemoteFromUrl sab a = withTmpDir "journal" $ \tmpdir -> do
 -- objects are deleted.
 cleanupInitialization :: StartAnnexBranch -> FilePath -> Annex ()
 cleanupInitialization sab alternatejournaldir = void $ tryNonAsync $ do
-	liftIO $ mapM_ removeFile =<< dirContents alternatejournaldir
+	liftIO $ mapM_ R.removeLink
+		=<< dirContents (toRawFilePath alternatejournaldir)
 	case sab of
 		AnnexBranchExistedAlready _ -> noop
 		AnnexBranchCreatedEmpty r ->