[clang] [Clang][OpenCL][AMDGPU] Allow a kernel to call another kernel (PR #115821)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

Also, if you're compiling C++26, why is it enabling OpenCL language features? You can already do this pretty easily with `clang --target=spirv64` so long as you're okay with using vendor intrinsic extensions in SPIR-V. That's pretty much what the HIP support for SPIR-V does anyways.

https://github.com/llvm/llvm-project/pull/115821