Revert "Revert adoption of CUDA indexing in general - this can only work with later versions of the compiler, just like module based dispatch, and thus must be guarded against usage in earlier (e.g. 1.6) versions."

This reverts commit d2fd1f5

samples/0_Intro/square/square.cu

@@ -40,8 +40,8 @@ template <typename T>
 __global__ void
 vector_square(T *C_d, const T *A_d, size_t N)
 {
-    size_t offset = (blockIdx.x * blockDim.x + threadIdx.x);
+    size_t offset = (hipBlockIdx_x * hipBlockDim_x + hipThreadIdx_x);
-    size_t stride = blockDim.x * gridDim.x ;
+    size_t stride = hipBlockDim_x * hipGridDim_x ;
 
     for (size_t i=offset; i<N; i+=stride) {
         C_d[i] = A_d[i] * A_d[i];