[llvm] Reland: [llvm-cov][WebAssembly] Read `__llvm_prf_names` from data segments (PR #112569)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> Unfortunately, it still fails with the same error. I also noticed other error messages I had missed in the past (but after checking, they were there on the first landing):
> 
> ```
> LLVM Profile Error: Invalid profile data to merge
> LLVM Profile Error: Profile Merging of file D:\task_172914326170851\fetches\llvm-project/build/profiles/10870457539148555413_0.profraw failed: File exists
> LLVM Profile Error: Failed to write file "D:\task_172914326170851\fetches\llvm-project/build/profiles/10870457539148555413_0.profraw": File exists
> ```

@glandium Is your PGO setup still broken, after the fixup/partial revert that was pushed in 157f10ddf2d851125a85a71e530dc9d50cb032a2? I.e. does this reapply attempt still break things for you, or are things still broken on main?

https://github.com/llvm/llvm-project/pull/112569