use locking on Windows

This is all the easy cases, where there was already a separate lock file.

Types/LockPool.hs

@@ -0,0 +1,24 @@
+{- git-annex lock pool data types
+ - 
+ - Copyright 2014 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+{-# LANGUAGE CPP #-}
+
+module Types.LockPool (
+	LockPool,
+	LockHandle
+) where
+
+import qualified Data.Map as M
+
+#ifndef mingw32_HOST_OS
+import System.Posix.Types (Fd)
+type LockHandle = Fd
+#else
+import Utility.WinLock -- defines LockHandle
+#endif
+
+type LockPool = M.Map FilePath LockHandle