In libxlDomainMigrationPrepare it is possible to dereference a NULL
libxlDomainObjPrivatePtr in early error paths. Check for a valid
'priv' before using it.
Signed-off-by: NJim Fehlig <jfehlig@suse.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>