qom: fix refcount of non-heap-allocated objects

The reference count for embedded objects is always one too low, because
object_initialize_with_type returns with zero references to the object.
This causes premature finalization of the object (or an assertion failure)
after calling object_ref to add an extra reference and object_unref to
remove it.

The fix is to move the initial object_ref call from object_new_with_type
to object_initialize_with_type.
Acked-by: NAndreas Färber <afaerber@suse.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

qom/object.c

@@ -307,6 +307,7 @@ void object_initialize_with_type(void *data, TypeImpl *type)
 
     memset(obj, 0, type->instance_size);
     obj->class = type->class;
+    object_ref(obj);
     QTAILQ_INIT(&obj->properties);
     object_init_with_type(obj, type);
 }
@@ -395,7 +396,6 @@ Object *object_new_with_type(Type type)
 
     obj = g_malloc(type->instance_size);
     object_initialize_with_type(obj, type);
-    object_ref(obj);
 
     return obj;
 }