*: 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/procps/top.c b/procps/top.c
index ec84374..fd75809 100644
--- a/procps/top.c
+++ b/procps/top.c
@@ -28,7 +28,7 @@
  * Copyright (C) 1994-1996 Charles L. Blake.
  * Copyright (C) 1992-1998 Michael K. Johnson
  *
- * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 
 #include "libbb.h"