CUDA: CUDAHOSTCXX Env (#16869)
CUDA: CUDAHOSTCXX Env (#16869)

This is a general CMake CUDA language hint to use the CXX
compiler has host compiler for NVCC. Seems like a good
default since we do not express the CUDA compiler in Spack
otherwise yet (e.g. no `self.compiler.cuda` or
`self.compiler.cudahostcxx`).
iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,LLNL/spack,LLNL/spack