Import new gnulib.

grub-core/gnulib/strnlen.c

@@ -1,5 +1,5 @@
 /* Find the length of STRING, but scan at most MAXLEN characters.
-   Copyright (C) 2005, 2006, 2007, 2009, 2010 Free Software Foundation, Inc.
+   Copyright (C) 2005-2007, 2009-2013 Free Software Foundation, Inc.
    Written by Simon Josefsson.
 
    This program is free software; you can redistribute it and/or modify
@@ -13,8 +13,7 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software Foundation,
-   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+   along with this program; if not, see <http://www.gnu.org/licenses/>.  */
 
 #include <config.h>