[llvm] [RemoveDIs] Load into new debug info format by default in llvm-lto and llvm-lto2 (PR #86271)

[J. Ryan Stinnett via llvm-commits]

jryans wrote:

> Using a branch for compiletimetracker (OCHyams perf/bitcodeloading) I reverted this patch, enabled bitcode writing by default, then relanded this patch. The stage1-ReleaseLTO-g config pasted below shows that it's not just the improvements from "enable bitcode writing by default" hiding the costs of this patch, but instead that combined together there's an improved reduction in compile time.
> 
> ```
> instructions:u
> 
> Commit     stage1-ReleaseLTO-g
> 2a4246645f 6062M (-0.87%) # This patch again
> f53953c6d2 6904M (-0.24%) # Enable bitcode writing by default
> ea3dff12f7 7140M (-0.68%) # Revert this patch
> b3f98dff75 7806M          # This patch
> ```

Ah, at first I was having trouble matching those numbers with ones [on the tracker](https://llvm-compile-time-tracker.com/index.php?config=Overview&stat=instructions%3Au&remote=OCHyams), but it looks like you've removed the "9" digit at the front of all the instruction counts. 😉 

Anyway, glad to see the compile time reduction! 😄 

https://github.com/llvm/llvm-project/pull/86271