move old ghc compat code into separate module; eliminate WITH_CLIBS

This avoids hsc2hs being run except when building for the old version of ghc.
Should speed up builds.

Utility/Touch.hs

@@ -0,0 +1,52 @@
+{- More control over touching a file.
+ -
+ - Copyright 2011 Joey Hess <id@joeyh.name>
+ -
+ - License: BSD-2-clause
+ -}
+
+{-# LANGUAGE CPP #-}
+
+module Utility.Touch (
+	TimeSpec(..),
+	touchBoth,
+	touch
+) where
+
+#if ! defined(mingw32_HOST_OS) && ! defined(__ANDROID__)
+
+#if MIN_VERSION_unix(2,7,0)
+
+import System.Posix.Files
+import System.Posix.Types
+
+newtype TimeSpec = TimeSpec EpochTime
+
+{- Changes the access and modification times of an existing file.
+   Can follow symlinks, or not. Throws IO error on failure. -}
+touchBoth :: FilePath -> TimeSpec -> TimeSpec -> Bool -> IO ()
+touchBoth file (TimeSpec atime) (TimeSpec mtime) follow
+	| follow = setFileTimes file atime mtime
+	| otherwise = setSymbolicLinkTimesHiRes file (realToFrac atime) (realToFrac mtime)
+
+touch :: FilePath -> TimeSpec -> Bool -> IO ()
+touch file mtime = touchBoth file mtime mtime
+
+#else
+import Utility.Touch.Old
+#endif
+
+#else
+
+import System.PosixCompat
+
+newtype TimeSpec = TimeSpec EpochTime
+
+{- Noop for Windows -}
+touchBoth FilePath -> TimeSpec -> TimeSpec -> Bool -> IO ()
+touchBoth _ _ _ _ = return ()
+
+touch :: FilePath -> TimeSpec -> Bool -> IO ()
+touch _ _ = return ()
+
+#endif