[llvm] [CMake] Enable CMP0179 alongside CMP0156 for deduplication on LLD (PR #116497)

[Fangrui Song via llvm-commits]

MaskRay wrote:

What is this deduplication issue and do you have a small reproduce? https://github.com/llvm/llvm-project/issues/116669 does not contain a reproduce. Archive semantics are special (https://maskray.me/blog/2021-06-20-symbol-processing#shared-object-overriding-archive)

https://github.com/llvm/llvm-project/pull/116497