Sema: fix empty struct init

* Extract common logic between `zirStructInitEmpty` and
   `zirStructInit`.
 * `resolveTypeFields` additionally sets status to `have_layout` if the
   total number of fields is 0.
88be5bd81dAndrew Kelley committed on 12/22/2021, 3:34:27 AMparent06d751d
4 files changedLine totals unavailable