[lld] [NFC][lld-macho] Generate test bodies for icf-safe-thunk tests (PR #111927)

[Peter Rong via llvm-commits]

DataCorrupted wrote:

I second @alx32 on this one. The script is nice, and I used it a lot. 

But it is useful only when the test and the outcome are straightforward, which doesn't seem to be the case here, e.g. the excessive attributes generated could be confusing.

BTW, I remember the script used to generate a leading line saying something like "this is auto generated, don't modify, blah", they don't do it anymore? Like [this one](https://github.com/llvm/llvm-project/blob/72fb37922577997f3666203dbdb2601f0fc97748/llvm/test/CodeGen/AArch64/aarch64_fnmadd.ll#L1-L2)


https://github.com/llvm/llvm-project/pull/111927