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

diff --git a/runit/runsv.c b/runit/runsv.c
index d5bfd4e..20f8495 100644
--- a/runit/runsv.c
+++ b/runit/runsv.c
@@ -30,7 +30,7 @@
 
 #include <sys/poll.h>
 #include <sys/file.h>
-#include "busybox.h"
+#include "libbb.h"
 #include "runit_lib.h"
 
 static int selfpipe[2];