app/testpmd: stop forwarding when quitting

When user quits testpmd, and there is traffic being forwarded,
that may produce a segmentation fault, due to ports being closed,
while they are still transmitting packets.

This patch prevents the issue from happening,
by stopping packet forwarding before closing the ports.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>

app/test-pmd/testpmd.c

@@ -1633,6 +1633,9 @@ pmd_test_exit(void)
 {
 	portid_t pt_id;
 
+	if (test_done == 0)
+		stop_packet_forwarding();
+
 	FOREACH_PORT(pt_id, ports) {
 		printf("Stopping port %d...", pt_id);
 		fflush(stdout);