`@import` that you have to configure in the build system first.

this makes porting projects gradually, file by file, rather cumbersome. now I have to rewrite quite a lot of Chocolate Doom because my port was halfway there and then @cImport got gutted... or keep going with Zig 0.16.2 until it's either 100% Zig or has little enough files that upgrading won't make my build.zig file implode in lines of code