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

[via cfe-commits]

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zeroomega wrote:

clang, opt and llvm-link are already added to extra_deps. 
L639-L645 looks redundant in this case

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