xcode从8升级到9出现的问题

为了使用iOS11，升级了xcode结果，TensorStorage.h里面报错，修改如下：

https://stackoverflow.com/questions/46356153/xcode-9-falls-to-build-partial-template-specialization-in-c

template<typename T, typename Dimensions, int Options_> class TensorStorage;

to

template<typename T, typename Dimensions, int Options_, typename empty = void> class TensorStorage;