qmp: Add deprecation information to query-machines

Export machine type deprecation status through the query-machines
QMP command.  With this, libvirt and management software will be
able to show this information to users and/or suggest changes to
VM configuration to avoid deprecated machines.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20190608233447.27970-2-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>