some warning fixes and cleanup

examples/connection_tester.cpp

@@ -225,7 +225,7 @@ struct peer_conn
 	}
 };
 
-int main(int argc, char const* argv[])
+int main(int argc, char* argv[])
 {
 	if (argc < 5)
 	{

examples/fragmentation_test.cpp

@@ -39,7 +39,7 @@ POSSIBILITY OF SUCH DAMAGE.
 
 using namespace libtorrent;
 
-int main(int argc, char const* argv[])
+int main(int argc, char* argv[])
 {
 	if (argc != 3 && argc != 2)
 	{