stage2: remove use of `builtin.stage2_arch` workaround

The LLVM backend no longer needs this hack! However, the other backends
still do. So there are still some traces of this workaround in use for now.
b0f80ef0d5Andrew Kelley committed on 10/14/2021, 1:43:43 AMparentdf7d6d2
5 files changedLine totals unavailable