[lld] [lld/COFF] Handle -start-lib / -end-lib better in /reproduce: output (PR #119752)

[Martin Storsjö via llvm-commits]

https://github.com/mstorsjo approved this pull request.

LGTM, this looks like a nice simplification! I wonder why it wasn't done like this from the get-go.

I remember running into some problems with some arguments around reproduce outputs as well, let's see if I remember them, now when you're digging around here :-)

With PDB outputs, I think the repro output has the problem that it will try to write the output into a directory that might not exist; this probably will need to be rewritten into something like just `/pdb:out.pdb` rather than the original PDB output path.

Then for really tricky things; if you have static libraries involved, that actually are thin libraries, i.e. just referencing other object files on disk, those aren't included in the repro package. And even if they would be, the static library would need to be rewritten to reference them with their relocatable name within the repro bundle.

https://github.com/llvm/llvm-project/pull/119752