Fix a memory leak introduced in the last release

The problem was this line:

	cleanup = and <$> sequence (map snd v)

That caused all of v to be held onto until the end, when the cleanup action
was run.

I could not seem to find a bang pattern that avoided the leak, so I
resorted to a IORef, rather clunky, but not a performance problem because
it will only be written once per git ls-files, so typically just 1 time.

This commit was sponsored by Mark Reidenbach on Patreon.

Utility/Path.hs

@@ -235,15 +235,11 @@ segmentPaths' f c (i:is) new =
  - than it would be to run the action separately with each path. In
  - the case of git file list commands, that assumption tends to hold.
  -}
-runSegmentPaths :: (a -> RawFilePath) -> ([RawFilePath] -> IO ([a], v)) -> [RawFilePath] -> IO ([[a]], v)
-runSegmentPaths c a paths = do
-	(l, cleanup) <- a paths
-	return (segmentPaths c paths l, cleanup)
+runSegmentPaths :: (a -> RawFilePath) -> ([RawFilePath] -> IO [a]) -> [RawFilePath] -> IO [[a]]
+runSegmentPaths c a paths = segmentPaths c paths <$> a paths
 
-runSegmentPaths' :: (Maybe RawFilePath -> a -> r) -> (a -> RawFilePath) -> ([RawFilePath] -> IO ([a], v)) -> [RawFilePath] -> IO ([[r]], v)
-runSegmentPaths' si c a paths = do
-	(l, cleanup) <- a paths
-	return (segmentPaths' si c paths l, cleanup)
+runSegmentPaths' :: (Maybe RawFilePath -> a -> r) -> (a -> RawFilePath) -> ([RawFilePath] -> IO [a]) -> [RawFilePath] -> IO [[r]]
+runSegmentPaths' si c a paths = segmentPaths' si c paths <$> a paths
 
 {- Converts paths in the home directory to use ~/ -}
 relHome :: FilePath -> IO String