[compiler-rt] Reapply "[compiler-rt][XRay] Make xray_interface.h C compliant" (PR #141728)

[Jan André Reuter via llvm-commits]

Thyre wrote:

@sebastiankreutzer, @MaskRay, sorry to ping you again.
The PR has been lying around for some time now. If you have time, could you take another look please?

https://github.com/llvm/llvm-project/pull/141728