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

[Matt Arsenault via cfe-commits]

arsenm wrote:

In practice this should be a single use of an internal function and should not require this hint. Is this papering over a different issue? 

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