[clang] [Clang][OpenCL][AMDGPU] OpenCL Kernel stubs should be assigned alwaysinline attribute (PR #137769)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> Why do you think it is an internal function? I thought it's an externally callable stub.

Yes at construction, but in the real optimization pipeline it will be internalized 

https://github.com/llvm/llvm-project/pull/137769