[llvm] [CodeGen] Teach ReplaceWithVeclib to use correct calling convention (PR #180773)

[David Sherwood via llvm-commits]

david-arm wrote:

Hi @paschalis-mpeis, you left a comment saying "Thanks for improving the patch, looks good!"

If you're happy with the patch would be ok to approve it? I've removed the outdated comment now.

https://github.com/llvm/llvm-project/pull/180773