[lld] [LLD] [COFF] Preserve directives and export names from LTO objects (PR #78802)

[Fangrui Song via llvm-commits]

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

I confirm that this fixes https://github.com/mstorsjo/llvm-mingw/files/13934972/repro.tar.gz (xz disguised as gz :))

https://github.com/llvm/llvm-project/pull/78802