Updated support for Zig

[dcbaker]

This is #8579 rebased and updated.

There are still a few TODO items (as noted in the TODO comment).

Additionally, zig itself has a couple of issue that make it difficult to integrate into Meson:

• Lack of depfile support (command-line: add option to generate a depfile when using zig build-obj/zig build-exe ziglang/zig#16850)
• the stdlib API changes across versions, and zig doesn't have a pre-processor to ease that, which makes writing tests that work across multiple versions of Zig hard.

Help with any of these issues is welcome.

[eli-schwartz]

the stdlib API changes across versions, and zig doesn't have a pre-processor to ease that, which makes writing tests that work across multiple versions of Zig hard.

It sounds like we have no choice but to use versioned sources depending on the return value of get_compiler('zig').version(). Yes, it's grotty, but also, it's doable. We will just need to continually add new versions of the test whenever the image builder tries to update to a new zig release.

[dcbaker]

I was thinking about just requiring C and calling c.preprocess(), lol

[eli-schwartz]

I assume that the main challenge is having to keep updating, rather than how many files we split the code text across. :D