[llvm] [llvm] Fix symbol name offset in parsing chained-fixup entry function (PR #83564)

[Fangrui Song via llvm-commits]

MaskRay wrote:

https://maskray.me/blog/2021-08-08-toolchain-testing#i-dont-know-where-to-add-a-test

> You can comment out code that your patch has modified, or make an intentional mistake, then run the whole testsuite to locate relevant tests. You can use git log -- file to learn the history of these tests.

The llvm-objdump Mach-O code generally has quite poor test coverage. So it's possible you cannot find the test immediately. You may need to study tests under llvm/test/Object and llvm/test/tools/llvm-objdump/MachO, and sometimes a refactoring before fixing an issue is useful.

https://github.com/llvm/llvm-project/pull/83564