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

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

Minus the XRay tests, all the failures reported here are on Darwin. Hoping to put patches up later today to get things working (will ping you all for review) and will then reland the enablement once those land.

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