[llvm] Add functionality to llvm-objcopy to remove prefixes (PR #79415)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

> If an object file has `a` and `za`, `llvm-objcopy --prefix-symbols-remove=z` would leave two `a`. If either one is STB_LOCAL, it should be fine. If both are STB_GLOBAL, the linker will likely report a duplicate definition error.

Thinking more about this, I think it's fair to allow it (it's not the first option where people can break their object files after all).

https://github.com/llvm/llvm-project/pull/79415