[clang] [Offload] Move HIP and CUDA to new driver by default (PR #84420)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> Do you mean the SPIR-V target (backend)? I have not followed this area of work closely. What is missing or what exactly needs to be supported by the SPIR-V target? Any help or pointers would be greatly appreciated!

I believe there was some work to port SYCL to work with the new driver, however I don't know that status of that. However what I need from `SPIR-V` is a target in clang that enables the SPIR-V toolchain. That is, if I do `clang --target=spriv-something-something foo.c` it will spit out some valid SPIR-V. This is because the `clang-linker-wrapper` internally uses this to invoke the device linker without duplicating a whole lot of logic. E.g. `clang --target=nvptx64-nvidia-cuda -march=sm_89 foo.o bar.o` will invoke `nvlink` to create an output `cubin` file.

https://github.com/llvm/llvm-project/pull/84420