[clang] [CIR][CUDA] Upstream device stub body emission and name mangling (PR #177790)

[Konstantinos Parasyris via cfe-commits]

https://github.com/koparasy commented:

Thanks for pushing on this! 

Overall comment, I would be more aggressive here and throw more NIY for the HIP cases. We are not testing those, so we should "abort" and leave it for some future PR. 

https://github.com/llvm/llvm-project/pull/177790