The idea here is that the zig2 executable is perhaps the more useful
deliverable until we implement our own optimization passes. This will
allow system packages to provide Zig, and use it to compile Zig
projects, all without LLVM!
When a zig compiler without LLVM extensions is satisfactory, this
greatly simplified build-from-source process can be used.
This could be useful for users who only want to contribute to the
standard library, for example.
