hammer2_dummy_xop_from_chain
void hammer2_dummy_xop_from_chain(hammer2_xop_head_t *xop,
hammer2_dummy_xop_from_chain(&xop, schain);
void hammer2_dummy_xop_from_chain(hammer2_xop_head_t *xop,
hammer2_dummy_xop_from_chain(&xop, schain);