[clang-driver] Default to offload-arch=amdgcnspirv for HIP/AMDGPU compilations #1361
Description
Once we enable the SPIRV backend by default, we can update the clang driver to default to amdgcnspirv as the offload-arch whenever we're compiling a HIP file (-x hip) or an AMDGPU triple is provided (--target=amdgcn-amd-amdhsa)
Effectively, clang -x hip file.hip --> clang --offload-arch=amdgcnspirv -x hip file.hip