Fix race

ggml/src/ggml-cuda/delta-net.cu

@@ -137,6 +137,9 @@ __global__ void delta_net_recurrent_f32(
             sum1 += all_sum1[i*WARP_SIZE_S + row];
             sum2 += all_sum2[i*WARP_SIZE_S + row];
         }
+        // To be honest, I don't understand why we need this sync. But without it I observe results varying from run to run
+        __syncthreads();
+
         float sv_new = beta_val * (v_ptr[t * qkv_stride_token + row_out] - sum1 * decay);
         if (col_idx_0 == 0) {
             out_base[t * out_token_stride + row_out] = sum2 * decay + sv_new * attn_score;