Update to a hopefully more future proof FSF address

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>

darwin-user/mmap.c

@@ -14,9 +14,7 @@
  *  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 <stdlib.h>
 #include <stdio.h>