*: make GNU licensing statement forms more regular

This change retains "or later" state! No licensing _changes_ here,
only form is adjusted (article, space between "GPL" and "v2" and so on).

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/include/libbb.h b/include/libbb.h
index 21e1441..ac818a9 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -3,9 +3,9 @@
  * Busybox main internal header file
  *
  * Based in part on code from sash, Copyright (c) 1999 by David I. Bell
- * Permission has been granted to redistribute this code under the GPL.
+ * Permission has been granted to redistribute this code under GPL.
  *
- * Licensed under the GPL version 2, see the file LICENSE in this tarball.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 #ifndef LIBBB_H
 #define LIBBB_H 1