Make domainslib build/run with OCaml 5.00 after PR #704

[bikallem]

Updated CI to use opam repo @ https://github.com/kit-ty-kate/multicore-opam. So that we can use the ocaml 5.00 switch. (4.14.0+domains).

This will probably need to be reverted to original multicore-opam once the changes from kit-ty-kate is merged.

Note: After this PR is merged domainslib will be incompatible with 4.12.0+domains switch. We need to cherry pick PR#704 from 5.00 branch to 4.12.0+domains branch. The latter is no longer the case after ocaml-multicore/ocaml-multicore#718

[bikallem]

ci with 5.00 works correctly. https://github.com/bikallem/domainslib/actions/runs/1372140682.

I am working on cherry-picking PR#704 to 4.12+domains/4.12+domains+effects. After which I will re-enable the ci for 4.12+domains branches again.

edit: converted the PR into a draft as I am still waiting for ocaml-multicore/ocaml-multicore#718 to be merged into 4.12.0+domains branches

[kayceesrk]

Note: After this PR is merged domainslib will be incompatible with 4.12.0+domains switch. We need to cherry pick PR#704 from 5.00 branch to 4.12.0+domains branch.

IINM for the Tezos work, @Sudha247 is using 4.12.0+domains, isn't it?

[Sudha247]

IINM for the Tezos work, @Sudha247 is using 4.12.0+domains, isn't it?

Yes, that's right. I think domainslib should work on 4.12.0+domains once ocaml-multicore/ocaml-multicore#718 is pushed to 4.12.0+domains branch.

[bikallem]

hurrah! ci is finally green with the latest 4.12+domains+effects and 4.12+domains switches.
ready for review.

/cc @Sudha247 @ctk21

[Sudha247]

Thanks! This looks good to go, barring a minor comment on mirage-clock-unix.

[Sudha247]

Merging.