Native runtime uses non tailrec functions which cause failure on large json

[Khady]

We faced at ahrefs a problem with json that contained large arrays. We have some segfaults because of Stdlib.List.map. This isn't a problem for people using ocaml 5, but it's still a problem with ocaml 4.

I did a quick fix for us
main...ahrefs:melange-json:louis/native-list-tailrec

The fact that melange_json.ml doesn't have a corresponding .mli meant that I couldn't just create a List module with the few necessary functions.