[compiler-rt] [libclc] [libcxx] [libcxxabi] [libunwind] [llvm] [CMake] Remove the use of AddLLVM from runtimes (PR #217502)

[via llvm-commits]

zeroomega wrote:

Looks like some runtime tests depends on functions from the "AddLLVM" : https://github.com/llvm/llvm-project/blob/cb5e1ce91a8aca87680d22a92430c6e896c93cb1/third-party/unittest/CMakeLists.txt#L75 and it broke a few presubmit builders.

https://github.com/llvm/llvm-project/pull/217502