Windows: Avoid using unix-compat's rename, which refuses to rename directories.

Opened a bug about this: https://github.com/jystic/unix-compat/issues/10

Utility/PosixFiles.hs

@@ -0,0 +1,30 @@
+{- POSIX files (and compatablity wrappers).
+ -
+ - This is like System.PosixCompat.Files, except with a fixed rename.
+ -
+ - Copyright 2014 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+{-# LANGUAGE CPP #-}
+
+module Utility.PosixFiles (
+	module X,
+	rename
+) where
+
+import System.PosixCompat.Files as X hiding (rename)
+
+#ifndef mingw32_HOST_OS
+import System.Posix.Files (rename)
+#else
+import System.Win32.File (moveFile)
+#endif
+
+{- System.PosixCompat.Files.rename on Windows calls renameFile,
+ - so cannot rename directories. Instead, use Win32 moveFile, which can. -}
+#ifdef mingw32_HOST_OS
+rename :: FilePath -> FilePath -> IO ()
+rename = moveFile
+#endif