When making ABI stability checks for an active domain, we need to make
sure we use the same migratable definition which virDomainGetXMLDesc
with the MIGRATABLE flag provides, otherwise the ABI check will fail.
This is implemented in the new qemuDomainCheckABIStability which takes a
domain object and generates the right migratable definition from it.
Signed-off-by: Jiri Denemark <jdenemar@redhat.com> Reviewed-by: Pavel Hrdina <phrdina@redhat.com>