[lld] [llvm] [DTLTO] support distributing bitcode from FatLTO objects (PR #176928)

[Ben Dunbobbin via llvm-commits]

bd1976bris wrote:

FYI: https://github.com/llvm/llvm-project/pull/178035 has been approved now. Once it's merged I'll re-try the backport here.

https://github.com/llvm/llvm-project/pull/176928