*: 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/util-linux/umount.c b/util-linux/umount.c
index a19f86c..7ba46ee 100644
--- a/util-linux/umount.c
+++ b/util-linux/umount.c
@@ -5,7 +5,7 @@
  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
  * Copyright (C) 2005 by Rob Landley <rob@landley.net>
  *
- * Licensed under GPL version 2, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 #include <mntent.h>
 #include <sys/mount.h>