get rid of __WINDOWS__, use mingw32_HOST_OS

The latter is harder for me to remember, but avoids build failures in code
used by the configure program.

Remote/Directory.hs

@@ -219,7 +219,7 @@ retrieveEncrypted d chunksize (cipher, enck) k f p = metered (Just p) k $ \meter
 
 retrieveCheap :: FilePath -> ChunkSize -> Key -> FilePath -> Annex Bool
 retrieveCheap _ (Just _) _ _ = return False -- no cheap retrieval for chunks
-#ifndef __WINDOWS__
+#ifndef mingw32_HOST_OS
 retrieveCheap d _ k f = liftIO $ withStoredFiles Nothing d k go
   where
 	go [file] = catchBoolIO $ createSymbolicLink file f >> return True

Remote/Git.hs

@@ -267,7 +267,7 @@ keyUrls :: Git.Repo -> Key -> [String]
 keyUrls r key = map tourl locs
   where
 	tourl l = Git.repoLocation r ++ "/" ++ l
-#ifndef __WINDOWS__
+#ifndef mingw32_HOST_OS
 	locs = annexLocations key
 #else
 	locs = map (replace "\\" "/") (annexLocations key)
@@ -361,7 +361,7 @@ copyFromRemote' r key file dest
 
 copyFromRemoteCheap :: Remote -> Key -> FilePath -> Annex Bool
 copyFromRemoteCheap r key file
-#ifndef __WINDOWS__
+#ifndef mingw32_HOST_OS
 	| not $ Git.repoIsUrl (repo r) = guardUsable (repo r) False $ do
 		loc <- liftIO $ gitAnnexLocation key (repo r) $
 			fromJust $ remoteGitConfig $ gitconfig r
@@ -418,7 +418,7 @@ rsyncHelper callback params = do
  - filesystem. Then cp could be faster. -}
 rsyncOrCopyFile :: [CommandParam] -> FilePath -> FilePath -> MeterUpdate -> Annex Bool
 rsyncOrCopyFile rsyncparams src dest p =
-#ifdef __WINDOWS__
+#ifdef mingw32_HOST_OS
 	dorsync
   where
 #else

Remote/Rsync.hs

@@ -11,7 +11,7 @@ module Remote.Rsync (remote) where
 
 import qualified Data.ByteString.Lazy as L
 import qualified Data.Map as M
-#ifndef __WINDOWS__
+#ifndef mingw32_HOST_OS
 import System.Posix.Process (getProcessID)
 #else
 import System.Random (getStdRandom, random)
@@ -221,7 +221,7 @@ sendParams = ifM crippledFileSystem
  - up trees for rsync. -}
 withRsyncScratchDir :: (FilePath -> Annex Bool) -> Annex Bool
 withRsyncScratchDir a = do
-#ifndef __WINDOWS__
+#ifndef mingw32_HOST_OS
 	v <- liftIO getProcessID
 #else
 	v <- liftIO (getStdRandom random :: IO Int)