As part of the jextract rewrite, jextract now hardwires offsets to struct fields in the bindings it generates. While this allows smoother startup, it is very inconvenient: if a struct layout needs to be hand-edited (e.g. to enable packing), all the offsets would become invalid.

It is recommended to switch to a scheme where instead of hardwired offsets, we just compute the offsets using the layout API (e.g. `MemoryLayout::byteOffset(PathElement...)`.