cgstructlitfill's `...` total read only an N_INTLIT dim node, so a
def-dimensioned [N]T struct field under-filled: elements 1..N-1 kept
the zero-fill, silently, wwstage only (cstage and the tn twin read
the stamped array length). Read tichase(fi.tnode.type_).alen first;
the surface node stays as the fallback for unstamped shapes.
