[llvm] [llvm-objcopy] Stream ELF output to reduce peak memory usage (PR #217706)

[Farid Zakaria via llvm-commits]

fzakaria wrote:

@jh7370 thank you for the feedback -- let me break up the stack and use GitHub new stack feature.
(I will keep this one the top or the base?.. not sure yet).

Let me do that, try to address the easy comments and then look at it again.

https://github.com/llvm/llvm-project/pull/217706