default devices: network

Add a default_net variable which specified whenever a default network
should be created.  It is cleared in case any -net option is specified
and it is also added to the new -nodefaults switch.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/net.h b/net.h
index d583d59..4971fcb 100644
--- a/net.h
+++ b/net.h
@@ -139,6 +139,7 @@
 
 extern int nb_nics;
 extern NICInfo nd_table[MAX_NICS];
+extern int default_net;
 
 /* BT HCI info */