[clang] [llvm] [clang][llvm][fatlto] Avoid cloning modules in FatLTO (PR #72180)

[Nikita Popov via cfe-commits]

nikic wrote:

I like the approach of saying that FatLTO implies UnifiedLTO. This nicely justifies why we are always using the ThinLTO pre-link pipeline.

https://github.com/llvm/llvm-project/pull/72180