CUDA: Add support for CUDA_ARCHITECTURES=native
CUDA 11.6 added the nvcc -arch=native
flag to automatically compile
for the host GPUs' architectures. Add support for specifying this
special native
value in CMAKE_CUDA_ARCHITECTURES
and
CUDA_ARCHITECTURES
. During the compiler ABI detection step,
detect the native architectures so we can pass them explicitly
when using Clang or older versions of nvcc.
Fixes: #22375 (closed)