Comment the need to match struct cblc_field_t with structs.cc

Trying to switch refer_fill_internal() to putting cblc_refer_t onto the
stack, rather than creating zillion static variables, remains a work
in progress.  This version is still vs_static, because vs_stack results
in intermittent failures.  Evidence suggests the data are still being
accessed after they are no longer available.  Or something.