[llvm] [XRay] Ignore debug instructions in instruction threshold (PR #219400)

[Yongqiang Tian via llvm-commits]

yqtian-se wrote:

Hi @optimisan, 

would you be able to take a look at this XRay instrumentation change, or suggest a more appropriate reviewer? It makes `xray-instruction-threshold` independent of debug-only MachineInstrs and includes regression coverage for both the legacy and new pass-manager paths. 

Thanks!

https://github.com/llvm/llvm-project/pull/219400