[compiler-rt] Fix compile error on ohos (PR #118193)

[Andrew Browne via llvm-commits]

browneee wrote:

Imo the correct solution here is fix openharmony os's sdk by adding the missing function.

This approach would be better for several reasons:

- If you don't fix OHOS musl installation, you'll eventually get similar issues when building other software that uses this function. Imo you'll probably save OHOS developes/users time by fixing the root cause.
- If you do this `#ifdef`, then later fix the OHOS sdk (add the missing function), people may hit issues where they have a version of llvm sources which `#ifdef` the function out, even though it is now present in OHOS.
- This `#ifdef` is polluting the sanitizer code with a tiny bit of extra complexity for a bug (afaict) in a relatively uncommon platform.
- It seems fair for you to say that you only support DFSan on OHOS for versions of OHOS after SDK is fixed (DFSan being more of a an optional-extra feature in LLVM, rather than something essential for compilation).

Was there any explanation from the openharmony community why this function was missing?

Between fixing openharmony sdk vs your latest patch, do you still feel your patch is the right solution?

https://github.com/llvm/llvm-project/pull/118193