[llvm] [NFC] Add a new Intrinsics.cpp file for intrinsic code (PR #110078)

[Rahul Joshi via llvm-commits]

jurahul wrote:

We could also rename Intrinsics.h to Intrinsic.h to match the namespace, but that may be too much busy work for questionable benefit.

https://github.com/llvm/llvm-project/pull/110078