[llvm-branch-commits] [compiler-rt] Default to Lit's Internal Shell (PR #165148)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/165148

All of the tests should work with the internal shell now, at least on
x86 Linux. Enable it by default for the performance/debuggability
advantages.