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

[Arthur Eubanks via llvm-commits]

aeubanks 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 LTO ones?

ThinLTO pre-link optimization pipeline should work for any IR that will go through another round of optimization later on.

Does this work for you?

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