* build.zig: remove detour through zig0. I'll add it back as an option
later. This means you can build stage1 with a freshly built zig
without detouring through zig0 again.
* remove unused file windows_script.bat
* drone.yml: remove unnecessary steps
* ninja doesn't need a jobs parameter
* build the release version of zig with zig build instead of cmake.
* build stage2 with -Dstatic-llvm -Duse-zig-libcxx
A new zsf-hosted server is being brought online.
This should be enough for linux build, test and packaging pipeline.
Currently this pipeline does not not post artifacts.