Merge pull request #21 from ubidefeo/patch-1

fix compiler complaint about `strptime`

Author: facchinm

src/NB.cpp

@@ -16,7 +16,7 @@
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
-
+#define _XOPEN_SOURCE
 #include <time.h>
 
 #include "Modem.h"