[build][Zig] Reviewed compatibility with latest zig master branch (v0.14.0)

[Joonsey]

defineCMacro is removed, this is my solution to get raylib to build with zig 0.14.0+2540

[HaxSam]

Shouldn't we wait until zig 0.14.0 is released?

[Joonsey]

Sure, can leave the mr open in any case until then maybe

[raysan5]

@Joonsey @HaxSam when is Zig 0.14.0 being released?

[Joonsey]

I'm unfamiliar, however they do very much recommend using master.

With a release cadance every ~6 months.

I can update this PR until release if that's preferred?

[HaxSam]

Also, the zig binding from @Not-Nik (raylib-zig) only uses the latest release from zig. See CONTRIBUTING.md
To keep compatibility with the raylib build.zig it would be preferential to do the same here.

[Not-Nik]

I do that so I don't have to keep updating the binding for each breaking master change, but since we JUST had a raylib release and a new Zig release is imminent it's fine to update the build.zig from my side. Zig being a very immature language forces me to switch to the -dev versions of raylib anyways, so in this I'd rather have an updated build file sooner than later :)