The libxl library allows a libxl_domain_config object to be serialized
from/to a JSON string. Use this to allow testing of the XML to
libxl_domain_config conversion process. Test XML is converted to
libxl_domain_config, which is then serialized to json. A json template
corresponding to the test XML is converted to a libxl_domain_config
object using libxl_domain_config_from_json(), and then serialized
back to json using libxl_domain_config_to_json(). The two json
docs are then compared.

Using libxl to convert the json template to a libxl_domain_config
object and then back to json provides a simple way to account for
any changes or additions to the json representation across Xen
releases.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>
[update to v3.5.0-rc1, improve error reporting, use /bin/true emulator]
Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>