[llvm] [llvm-objcopy] Add SystemZ support (PR #81841)

[via llvm-commits]

llvmbot wrote:

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>/cherry-pick https://github.com/llvm/llvm-project/commit/3c02cb7492fc78fb678264cebf57ff88e478e14f

Error: Command failed due to missing milestone.

https://github.com/llvm/llvm-project/pull/81841