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

diff --git a/procps/sysctl.c b/procps/sysctl.c
index 2c3fda5..a0e9e16 100644
--- a/procps/sysctl.c
+++ b/procps/sysctl.c
@@ -14,7 +14,7 @@
  *
  */
 
-#include "busybox.h"
+#include "libbb.h"
 
 /*
  *    Function Prototypes