Sort includes and more cleanup and fixes in util/

du.c

@@ -1,13 +1,13 @@
 /* See LICENSE file for copyright and license details. */
-#include <sys/types.h>
-#include <sys/stat.h>
 #include <dirent.h>
-#include <unistd.h>
-#include <stdio.h>
-#include <string.h>
-#include <stdlib.h>
-#include <stdbool.h>
 #include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
 
 #include "util.h"