[llvm] [llvm-objcopy] Support SREC output format (PR #75874)

[Simon Tatham via llvm-commits]

https://github.com/statham-arm requested changes to this pull request.

This looks _almost_ fine to me now. I have only one remaining nitpick, and I apologise for not having spotted it the first time.

https://github.com/llvm/llvm-project/pull/75874