libxl: convert DefineXMLFlags to use begin/end API pattern
Similar to other uses of virDomainObjListAdd, on success add a ref to the
virDomainObj so that virDomainObjEndAPI can be called as usual.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>