Fix forgotten license comments

diff --git a/selinux/setsebool.c b/selinux/setsebool.c
index 83e70e2..b615ce7 100644
--- a/selinux/setsebool.c
+++ b/selinux/setsebool.c
@@ -4,6 +4,8 @@
  * NOTE: -P option requires libsemanage, so this feature is
  * omitted in this version
  * Yuichi Nakamura <ynakam@hitachisoft.jp>
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
  */
 
 #include "libbb.h"