Add a EIGEN_NO_CUDA option, and introduce EIGEN_CUDACC and EIGEN_CUDA_ARCH aliases

unsupported/Eigen/CXX11/src/Tensor/TensorRandom.h

@@ -16,7 +16,7 @@ namespace internal {
 namespace {
 
 EIGEN_DEVICE_FUNC uint64_t get_random_seed() {
-#ifdef __CUDA_ARCH__
+#ifdef EIGEN_CUDA_ARCH
   // We don't support 3d kernels since we currently only use 1 and
   // 2d kernels.
   assert(threadIdx.z == 0);