Architecture 30 was removed with CUDA 11, so most of the CUDA tests fail with
it.
Remove setting the architecture and bump the minimum version to 3.18, so
CMP0104 takes effect and we can rely on the default architecture, which is
guaranteed to be compilable.
Use of __ldg() in ProperLinkFlags was removed as it only affects performance
and is available only on sm_35 and above.
Testing the functionality of CUDA_ARCHITECTURES is already covered by
CudaOnly.Architecture and CudaOnly.CompileFlags.
The nvcc device linker is designed so that each static library
with device symbols only needs to be listed once as it doesn't
care about link order. If you provide the same static library
multiple times it will error out. To make sure this occurs
we find the unique set of link items.
