I reproduced the problem as well. The issue arises when we need to bootstrap a compiler in order to do the build because the host toolchain is too old, i.e., these messages get printed:

I can't reproduce the problem described in the change description. I had no problems building and booting a riscv VM on an arm64 system running commit d9e2caccfac1. I ran:

lib/clang gets added because we need lib/clang/libllvm, but we shouldn't need to build anything else under lib/clang in this phase. libclang should only be for MK_CLANG or MK_LLDB. Can you see why we're including it?