net: hub: suppress warnings of no host network for qtest

If we want to qtest through hub, it would be much more simpler and
safer to configure the hub without host network. So silent this
warnings for qtest.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 20181204035347.6148-3-jasowang@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

net/hub.c

@@ -20,6 +20,7 @@
 #include "hub.h"
 #include "qemu/iov.h"
 #include "qemu/error-report.h"
+#include "sysemu/qtest.h"
 
 /*
  * A hub broadcasts incoming packets to all its ports except the source port.
@@ -346,7 +347,7 @@ void net_hub_check_clients(void)
         if (has_host_dev && !has_nic) {
             warn_report("hub %d with no nics", hub->id);
         }
-        if (has_nic && !has_host_dev) {
+        if (has_nic && !has_host_dev && !qtest_enabled()) {
             warn_report("hub %d is not connected to host network", hub->id);
         }
     }