avoid unix-compat's rename

On Windows, that does not support long paths
https://github.com/jacobstanley/unix-compat/issues/56

Instead, use System.Directory.renamePath, which does support long paths.

Sponsored-by: Dartmouth College's Datalad project

Database/Init.hs

@@ -45,7 +45,7 @@ initDb db migration = do
 	setAnnexFilePerm tmpdb
 	liftIO $ do
 		void $ tryIO $ removeDirectoryRecursive (fromRawFilePath dbdir)
-		rename (fromRawFilePath tmpdbdir) (fromRawFilePath dbdir)
+		R.rename tmpdbdir dbdir
 
 {- Make sure that the database uses WAL mode, to prevent readers
  - from blocking writers, and prevent a writer from blocking readers.