[clang] [LinkerWrapper] Fix resolution of weak symbols during LTO (PR #68215)

[Jon Chesterfield via cfe-commits]

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

LinkerWrapper turning into a linker is kind of inevitable and not a very happy thing.

One option would be to lean on lld for amdgpu and split out the nvptx stuff in the hopes that we eventually have an alternative to nvlink, but it seems moderately unlikely to come to pass and driving both amdgpu and nvptx down the same code path has merits.

https://github.com/llvm/llvm-project/pull/68215