Define bracketOnError in compat; fixes the build for GHC 6.4

Distribution/Compat/Exception.hs

-{-# LANGUAGE CPP #-}
-{-# OPTIONS_GHC -cpp #-}
-{-# OPTIONS_NHC98 -cpp #-}
-{-# OPTIONS_JHC -fcpp #-}
--- #hide
-module Distribution.Compat.Exception (bracketOnError) where
-
-import Control.Exception as Exception
-
-#if defined(__GLASGOW_HASKELL__) && (__GLASGOW_HASKELL__ < 606)
-bracketOnError
-        :: IO a         -- ^ computation to run first (\"acquire resource\")
-        -> (a -> IO b)  -- ^ computation to run last (\"release resource\")
-        -> (a -> IO c)  -- ^ computation to run in-between
-        -> IO c         -- returns the value from the in-between computation
-bracketOnError before after thing =
-  Exception.block (do
-    a <- before
-    Exception.catch
-        (Exception.unblock (thing a))
-        (\e -> do { after a; Exception.throw e }))
-#endif
-

Distribution/Simple/Utils.hs

@@ -137,7 +137,7 @@ import System.IO
 import System.IO.Error as IO.Error
     ( try )
 import qualified Control.Exception as Exception
-    ( bracket, bracket_, catch, finally )
+    ( bracket, bracket_, bracketOnError, catch, finally )
 
 import Distribution.Text
     ( display )
@@ -159,7 +159,6 @@ import qualified Control.Exception as Exception
     ( throwIO )
 #endif
 
-import Distribution.Compat.Exception as Exception (bracketOnError)
 import Distribution.Compat.TempFile (openTempFile, openBinaryTempFile)
 import Distribution.Verbosity