Field_iterator_table_ref::set_field_iterator

Several functions that processed different prepare statements missed
the DT_INIT flag in last parameter of the open_normal_and_derived_tables()
calls. It made context analysis of derived tables dependent on the order in
which the derived tables were processed by mysql_handle_derived(). This
order was induced by the order of SELECTs in all_select_list.
In 10.4 the order of SELECTs in all_select_list became different and lack
of the DT_INIT flags in some open_normal_and_derived_tables() call became
critical as some derived tables were not identified as such.