usage.c: remove reference to busybox.h
*: s/include "busybox.h"/include "libbb.h"

diff --git a/util-linux/losetup.c b/util-linux/losetup.c
index b1e4b08..e2d4e4d 100644
--- a/util-linux/losetup.c
+++ b/util-linux/losetup.c
@@ -8,9 +8,8 @@
  */
 
 #include <getopt.h>
-#include <stdlib.h>
 
-#include "busybox.h"
+#include "libbb.h"
 
 int losetup_main(int argc, char **argv);
 int losetup_main(int argc, char **argv)