fsck: sort files alphabetically again

This makes fsck runs deterministic again.

Sorting (commit quoted below) got lost while
moving to go-fuse v2 api.

commit e6caf56ea4ab10e747aa5dfc0a768cb8176ebe6a
Author: Jakob Unterwurzacher <jakobunt@gmail.com>
Date:   Mon Apr 2 16:56:29 2018 +0200

    fsck: sort files alphabetically

    This makes fsck runs deterministic.

1 files changed, 3 insertions, 15 deletions

diff --git a/fsck.go b/fsck.go
index 1f40514..388071f 100644
--- a/fsck.go
+++ b/fsck.go
@@ -8,7 +8,7 @@ import (
 	"os"
 	"os/signal"
 	"path/filepath"
-	"strings"
+	"sort"
 	"sync"
 	"syscall"
 
@@ -96,6 +96,8 @@ func (ck *fsckObj) dir(relPath string) {
 		ck.markCorrupt(relPath)
 		return
 	}
+	// Sort alphabetically to make fsck runs deterministic
+	sort.Strings(entries)
 	for _, entry := range entries {
 		if ck.abort {
 			return
@@ -321,20 +323,6 @@ func fsck(args *argContainer) (exitcode int) {
 	return exitcodes.FsckErrors
 }
 
-type sortableDirEntries []fuse.DirEntry
-
-func (s sortableDirEntries) Len() int {
-	return len(s)
-}
-
-func (s sortableDirEntries) Swap(i, j int) {
-	s[i], s[j] = s[j], s[i]
-}
-
-func (s sortableDirEntries) Less(i, j int) bool {
-	return strings.Compare(s[i].Name, s[j].Name) < 0
-}
-
 func inum(f *os.File) uint64 {
 	var st syscall.Stat_t
 	err := syscall.Fstat(int(f.Fd()), &st)