libxl_device handling for nic and vtmp

[Olaf Hering <olaf@aepfle.de>]

What is the point of libxl__update_config_nic and
libxl__update_config_vtmp?

In libxl__device_type_add (called from DEFINE_DEVICE_ADD) the input
type is copied with libxl_device_type_copy to type_saved, which is a
1:1 copy. If needed, a new devid is assigned to the input. Later the
copy is updated with one of the two helper functions mentioned above.
But the helpers do not only update devid, also mac or uuid.

To me it looks like the double assignment can be removed. The new
pvusb code does not do it this way, it makes a copy of the fully
initialized type.

Perhaps the two helpers are useful in the context of domcreate_complete,
I have not reviewed that part of the code.


Olaf