[llvm] [Instrumentation] Mark instrumented calls as implicit (PR #106447)

[via llvm-commits]

serge-sans-paille wrote:

The change dates back to 201733b7f0b4fee6120dc1e0e43df90a860a34be, and I agree with the simplicity of your approach, let me update the diff.

https://github.com/llvm/llvm-project/pull/106447