[new release] eio_main, eio_luv, eio_linux and eio (0.8.1)

[talex5]

CHANGES:

Some build fixes:

• Fix build on various architectures (@talex5 Fix various architectures ocaml-multicore/eio#432).

  • Work around dune %{system} bug.
  • eio_luv: fix max_luv_buffer_size on 32-bit platforms.

• Add missing test-dependency on MDX (@talex5 Add missing test-dependency on MDX ocaml-multicore/eio#430).

[talex5]

• s390x-ocaml-5.0 is expected to fail for eio_luv (until Write fails on s390x (size_t vs uint) aantron/luv#144 is fixed). However, s390x should pass for eio_main, which uses eio_linux by default instead, so this isn't a big problem.
• The lwt_eio revdep tests are likely to time out (until SIGSEGV on OCaml 5 due to missing SA_ONSTACK ocsigen/lwt#981 is fixed).

[talex5]

I think this is ready to merge now. The two expected failures correspond to real bugs in other libraries, and the mac failure (Uncaught exception: Failure("\"rsync\") is unrelated.

[raphael-proust]

I made #23271 to mark luv as not available on s390x.

@talex5 do you think that's the appropriate change to make? Do you know if the error exists also for ocaml≠5?

[talex5]

I made #23271 to mark luv as not available on s390x.

I'd slightly prefer not to do that. eio_main depends on eio_luv (as a fallback) and making luv uninstallable will therefore prevent eio_main from working in all cases.

But I don't think we have any users on s390x yet, so it's not a big problem.

[kit-ty-kate]

Thanks