*: 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/modutils/modutils.c b/modutils/modutils.c
index 850a868..2608182 100644
--- a/modutils/modutils.c
+++ b/modutils/modutils.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2008 by Timo Teras <timo.teras@iki.fi>
  *
- * 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.
  */
 #include "modutils.h"