Update for Zig v0.14

[daniel-ac-martin]

This is what I believe are minimal changes to update this repo to work with the current version of Zig.

(It might be jumping the gun to update to v0.14 at this stage, but it's probably more useful than v0.7.)

Note that -O ReleaseSmall is required (although I think that -O ReleaseFast also works). Without this we get the following error:

error: Invalid record (Producer: 'zig 0.14.0' Reader: 'LLVM 19.1.4')