[llvm] [llvm-profdata] Enabled functionality to write split-layout profile (PR #101795)

[William Junda Huang via llvm-commits]

huangjd wrote:

> A drive-by comment, what's the use case to write split-layout profile?

ThinLTO uses samples with inlined functions to decide whether to perform inline or not, so samples without inlined functions are useless in this stage, we gather them in one section so that they can be skipped entirely without building a funcoffsettable for them 

https://github.com/llvm/llvm-project/pull/101795