[lld] [NFC][lld][ELF] Allow customized reproduce path (PR #151656)

[Haohai Wen via llvm-commits]

HaohaiWen wrote:

> I don't understand the change. The ELF port already respects `LLD_REPRODUCE`

We'd like to linker to auto create tar name based on output instead of manually specify a different reproduce flag every time. That requires to store its temporary name. I don't know whether community is interested in that.

I know this PR looks weird for unnecessary copy. If that is not acceptable, I can upstream this change until we really need to create a temporary name.

https://github.com/llvm/llvm-project/pull/151656