[clang] [llvm] [DTLTO] Serialize of LTO Config (PR #219894)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

To be explicit I think this is moving in the wrong direction and is not a viable starting point. Toolchain machinery flags should not be serialized, and any semantic or ABI influencing options need white-glove, independent treatment 

https://github.com/llvm/llvm-project/pull/219894