[compiler-rt] Reapply "[compiler-rt] Default to Lit's Internal Shell" (PR #168232)

[Dan Blackwell via llvm-commits]

DanBlackwell wrote:

I think this commit has caused a number of test failures on Green Dragon (Apple OS CI testing): https://green.lab.llvm.org/job/llvm.org/job/clang-stage1-RA/5985/.

https://github.com/llvm/llvm-project/pull/168232