*: 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>

libbb/fclose_nonstdin.c

@@ -4,7 +4,7 @@
  *
  * Copyright (C) 2003  Manuel Novoa III  <mjn3@codepoet.org>
  *
- * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
 /* A number of standard utilities can accept multiple command line args