windows back to lts-18.13 temporarily

I can't seem to get stack to resolve dependencies with Win32-2.13.4.0,
no matter what I try. Why it blows up, I don't know.

And allow-newer: true actually causes it to downgrade Win32 to the one
version that won't build. Unbelivable that allows downgrades.

So just gonna have to wait for that to get into stackage nightly, and
then stack.yaml can be updated to use that, and the changes in this
commit reverted.

Utility/LockFile/Windows.hs

@@ -5,7 +5,7 @@
  - License: BSD-2-clause
  -}
 
-{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE OverloadedStrings, CPP #-}
 
 module Utility.LockFile.Windows (
 	lockShared,
@@ -58,12 +58,21 @@ lockExclusive = openLock fILE_SHARE_NONE
 openLock :: ShareMode -> LockFile -> IO (Maybe LockHandle)
 openLock sharemode f = do
 	f' <- convertToWindowsNativeNamespace f
+#if MIN_VERSION_Win32(2,13,4)
 	r <- tryNonAsync $ createFile_NoRetry f' gENERIC_READ sharemode 
 		security_attributes oPEN_ALWAYS fILE_ATTRIBUTE_NORMAL
 		(maybePtr Nothing)
 	return $ case r of
 		Left _ -> Nothing
 		Right h -> Just h
+#else
+	h <- withTString (fromRawFilePath f') $ \c_f ->
+		c_CreateFile c_f gENERIC_READ sharemode security_attributes
+			oPEN_ALWAYS fILE_ATTRIBUTE_NORMAL (maybePtr Nothing)
+	return $ if h == iNVALID_HANDLE_VALUE
+		then Nothing
+		else Just h
+#endif
   where
 	security_attributes = maybePtr Nothing