[clang] [llvm] [CGData][ThinLTO] Global Outlining with Two-CodeGen Rounds (PR #90933)

[Kyungwoo Lee via cfe-commits]

kyulee-com wrote:

> IIUC, we must use `-codegen-data-generate` and `-codegen-data-use` in the profiled and post-link build, respectively, whereas they are done in the same build here.

@rlavaee It is not strictly necessary to run both `-codegen-data-generate` and `-codegen-data-use` for each profile and post-link build. Running `-codegen-data-use` only in the post-link build (using the same codegen data file saved from the profile build) should be fine, although it might impact some efficiency in size

https://github.com/llvm/llvm-project/pull/90933