[llvm] [llvm-objdump] Implement decoding auxiliary header for xcoff with llvm-objdump --private-headers (PR #105682)

[James Henderson via llvm-commits]

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+## Test that `the llvm-objdump --private-headers` print out the auxiliary header of XCOFF object file.
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jh7370 wrote:

Please review what I've said in your past reviews about providing comments for individual cases within the test, ordering of RUN/YAML/CHECK lines and whitespace (especially blank lines), and act on them in this test file too.

Have you run this test locally at all?

https://github.com/llvm/llvm-project/pull/105682