[llvm] [LTO] Add an option to select a pre-link pipeline (PR #82585)

[Igor Kudrin via llvm-commits]

igorkudrin wrote:

> Couldn't this also be achieved by using something like `-opt-pipeline='thinlto-pre-link<O3>'`?

What if the input set contains not only ThinLTO files but also regular ones?

https://github.com/llvm/llvm-project/pull/82585