[llvm] Expose TimeTraceProfiler for Async Events (PR #83778)

[Takuto Ikuta via llvm-commits]

atetubou wrote:

@MaskRay thank you for taking a look. If this looks good to you, could you merge this PR?
I'll rebase https://github.com/llvm/llvm-project/pull/83961 when this is merged.

https://github.com/llvm/llvm-project/pull/83778