Support `AnyDependency<void*>`.
Support `AnyDependency<void*>`.

By letting the result of `operator*` use `DependentPtr` instead of `Ptr`, it
does not break the whole build by forming a reference to `void` if `Ptr` is
`void*`. The reference would be formed only if `operator*` was used.

PiperOrigin-RevId: 480981726

google/riegeli,google/riegeli,google/riegeli,google/riegeli