*: 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/include/unicode.h b/include/unicode.h
index e9e2bd1..1dd55e6 100644
--- a/include/unicode.h
+++ b/include/unicode.h
@@ -1,6 +1,6 @@
 /* vi: set sw=4 ts=4: */
 /*
- * Licensed under the GPL version 2, see the file LICENSE in this tarball.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 #ifndef UNICODE_H
 #define UNICODE_H 1