[llvm] [llvm-objcopy] Add support of symbol modification flags for MachO (PR #120895)

[James Henderson via llvm-commits]

https://github.com/jh7370 approved this pull request.

LGTM from my point of view, but please wait for @alexander-shaposhnikov, as I don't know Mach-O really, so can't comment on the format-specific details.

https://github.com/llvm/llvm-project/pull/120895