Add NDEBUG flag to non-debug builds

[chip2n]

I noticed that the performance of web builds was terrible due to a lot of calls to glGetError, which as far as I can tell shouldn't be called in release builds at all. Turns out SOKOL_DEBUG is defined even when using -Doptimize=ReleaseSafe. I may be missing something obvious, but shouldn't NDEBUG be defined in this case? 👀

[floooh]

Hmm, interesting that Zig doesn't define that automatically in release builds.

Also looks like the latest Zig nightly broke the bindings, I'll need to to look into that first.

[chip2n]

Seems like Zig does define it for ReleaseFast and ReleaseSmall (https://github.com/ziglang/zig/blob/f38d7a92cc1ca8059ba909a82f2f944966b52296/src/Compilation.zig#L5943), but not for ReleaseSafe.

I guess ReleaseSafe does imply having more safeguards in place, so using glGetError kind of makes sense (and I don't see any difference in performance when building for desktop). However, I'd love to be able to do my web builds with ReleaseSafe for the standard safety stuff Zig does, while avoiding glGetError calls on the Sokol side.

[floooh]

Yeah totally makes sense (both Zig's ReleaseSafe behaviour, and not wanting to run glGetError in ReleaseSafe) - it will also disable the asserts in the C code, but I guess that's also fine and expected.

The CI error was about a naming convention change btw, but now I'm seeing a more mysterious problem with the Windows version (all unrelated to your PR, so don't worry, but I want to get the sokol-zig CI green again first before merging your PR).

[floooh]

..and merged. Thanks!