usage.c: remove reference to busybox.h

*: s/include "busybox.h"/include "libbb.h"

sysklogd/klogd.c

@@ -17,7 +17,7 @@
  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  */
 
-#include "busybox.h"
+#include "libbb.h"
 #include <sys/syslog.h>
 #include <sys/klog.h>
 

sysklogd/logger.c

@@ -7,7 +7,7 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-#include "busybox.h"
+#include "libbb.h"
 
 #if !defined CONFIG_SYSLOGD
 

sysklogd/logread.c

@@ -9,7 +9,7 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-#include "busybox.h"
+#include "libbb.h"
 #include <sys/ipc.h>
 #include <sys/sem.h>
 #include <sys/shm.h>

sysklogd/syslogd.c

@@ -13,7 +13,7 @@
  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  */
 
-#include "busybox.h"
+#include "libbb.h"
 #include <paths.h>
 #include <sys/un.h>