[llvm] [SystemZ][z/OS] Add z/OS archive writing support (PR #200087)

[James Henderson via llvm-commits]

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jh7370 wrote:

It looks to me like this file could do with some tests for the symbol table. In particular that a symbol table is correctly written when needed and otherwise the empty symbol table stuff is written correctly.

https://github.com/llvm/llvm-project/pull/200087