Sema: fix a few indexing bugs

* Indexing zero-bit types should not produce AIR indexing instructions
* Getting a runtime-known element pointer from a many-pointer should
  check that the many-pointer is not comptime-only

Resolves: #23405
bee19572c8mlugg committed on 4/28/2025, 6:48:24 PM· committed by Alex Rønne Petersenparentb5c2277
3 files changedLine totals unavailable