*: 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>

findutils/Kbuild.src

@@ -2,7 +2,7 @@
 #
 # Copyright (C) 1999-2005 by Erik Andersen <andersen@codepoet.org>
 #
-# Licensed under the GPL v2, see the file LICENSE in this tarball.
+# Licensed under GPLv2, see file LICENSE in this source tree.
 
 lib-y:=
 

findutils/find.c

@@ -7,7 +7,7 @@
  * Reworked by David Douthitt <n9ubh@callsign.net> and
  *  Matt Kraai <kraai@alumni.carnegiemellon.edu>.
  *
- * Licensed under the GPL version 2, see the file LICENSE in this tarball.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 
 /* findutils-4.1.20:

findutils/grep.c

@@ -5,7 +5,7 @@
  * Copyright (C) 1999,2000,2001 by Lineo, inc. and Mark Whitley
  * Copyright (C) 1999,2000,2001 by Mark Whitley <markw@codepoet.org>
  *
- * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 /* BB_AUDIT SUSv3 defects - unsupported option -x "match whole line only". */
 /* BB_AUDIT GNU defects - always acts as -a.  */

findutils/xargs.c

@@ -9,7 +9,7 @@
  * - Mike Rendell <michael@cs.mun.ca>
  * and David MacKenzie <djm@gnu.ai.mit.edu>.
  *
- * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  *
  * xargs is described in the Single Unix Specification v3 at
  * http://www.opengroup.org/onlinepubs/007904975/utilities/xargs.html