[llvm] [Offload][OMPT] Add callbacks for (dis)associate_ptr (PR #99046)

[Michael Halkenhäuser via llvm-commits]

https://github.com/mhalk approved this pull request.

LGTM.

Note: Only had the chance to test this for amdgpu.
It seemed to me as if it would try to build for nvptx when running `check-offload` even when no corresponding targets were available, resulting in a fail. (Unsure. Maybe just a misconfiguration on my side.)

https://github.com/llvm/llvm-project/pull/99046