convert to withCreateProcess for async exception safety

This handles all createProcessSuccess callers, and aside from process
pools, the complete conversion of all process running to async exception
safety should be complete now.

Also, was able to remove from Utility.Process the old API that I now
know was not a good idea. And proof it was bad: The code size went *down*,
despite there being a fair bit of boilerplate for some future API to
reduce.

Git/Queue.hs

@@ -191,10 +191,11 @@ runAction repo (UpdateIndexAction streamers) =
 	liftIO $ Git.UpdateIndex.streamUpdateIndex repo $ reverse streamers
 runAction repo action@(CommandAction {}) = liftIO $ do
 #ifndef mingw32_HOST_OS
-	let p = (proc "xargs" $ "-0":"git":toCommand gitparams) { env = gitEnv repo }
-	withHandle StdinHandle createProcessSuccess p $ \h -> do
-		hPutStr h $ intercalate "\0" $ toCommand $ getFiles action
-		hClose h
+	let p = (proc "xargs" $ "-0":"git":toCommand gitparams)
+		{ env = gitEnv repo
+		, std_in = CreatePipe
+		}
+	withCreateProcess p (go p)
 #else
 	-- Using xargs on Windows is problematic, so just run the command
 	-- once per file (not as efficient.)
@@ -206,6 +207,11 @@ runAction repo action@(CommandAction {}) = liftIO $ do
   where
 	gitparams = gitCommandLine
 		(Param (getSubcommand action):getParams action) repo
+	go p _ (Just h) _ pid = do
+		hPutStr h $ intercalate "\0" $ toCommand $ getFiles action
+		hClose h
+		forceSuccessProcess p pid
+	go _ _ _ _ _ = error "internal"
 runAction repo action@(InternalAction {}) =
 	let InternalActionRunner _ runner = getRunner action
 	in runner repo (getInternalFiles action)