OCaml 5.3 compatibility

[andyli]

Debian and Fedora have upgraded their OCaml to 5.3 in their distros, and the Haxe packages failed to build.

A Fedora packager, Jerry James, provided a patch, which can be applied on Haxe 4.3.4.
https://src.fedoraproject.org/rpms/haxe/blob/f42/f/haxe-ocaml5.3.patch

I've checked the patch can be applied on Haxe 4.3.6, but there is still a few compilation errors.

It would be great if a full fix can be made on the 4.3_bugfix and development branches. I will then turn the commit into a patch for packaging.

[kLabz]

I made 4.3_bugfix_ocaml5_2025 branch based off 4.3.6, where linux arm64 still fails to build (and macos-hl tests don't work), does that help? CI run

(I'll include this in 4.3_bugfix at some point but I'll also need to get CI green; might need to pull more updates from development)

[andyli]

Yes, that worked. Thanks!