*: 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/networking/hostname.c b/networking/hostname.c
index 121ad40..66b52dd 100644
--- a/networking/hostname.c
+++ b/networking/hostname.c
@@ -7,7 +7,7 @@
  * Adjusted by Erik Andersen <andersen@codepoet.org> to remove
  * use of long options and GNU getopt.  Improved the usage info.
  *
- * 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 "libbb.h"