Can't build libcxx alone, it requres libcxxabi

I am observing the libcxx project can not be built without libcxxabi, but
I thought libcxx should not depend upon other projects. Observed on x86.

Are you checking out the LLVM monorepo? I think the components are
interdependent on each other during configuration stages to some
extent, regardless of whether you use libcxxabi or libc++sup or
Pathscale libcxxrt.

Yes, monorepo, that’s why I’m wondering. I believe it is easily reproducible with the current state of trunk.