*: 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/busybox.h b/include/busybox.h
index 48fc0b4..76415dd 100644
--- a/include/busybox.h
+++ b/include/busybox.h
@@ -2,7 +2,7 @@
 /*
  * Busybox main internal header file
  *
- * 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.
  */
 #ifndef BUSYBOX_H
 #define BUSYBOX_H 1