[llvm] [memprof] Update YAML traits for writer purposes (PR #118720)

[via llvm-commits]

dyung wrote:

@kazutakahirata, this seems to fail to build on macOS, can you take a look?
- https://lab.llvm.org/buildbot/#/builders/190/builds/10737
- https://lab.llvm.org/buildbot/#/builders/23/builds/5491

https://github.com/llvm/llvm-project/pull/118720