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

[Fangrui Song via llvm-commits]

MaskRay wrote:

GNU objcopy does not support the option. I filed https://sourceware.org/bugzilla/show_bug.cgi?id=16773

If an object file has `a` and `za`, `llvm-objcopy --prefix-symbols-remove=z` would leave to 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.

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