fix clang-tidy
fix clang-tidy

xchainer/indexable_array.h:175:39: error: The right operand of '*' is a garbage value due to array index out of bounds [clang-analyzer-core.UndefinedBinaryOperatorResult,-warnings-as-errors]
            data_ptr += strides_[dim] * index[dim];
                                      ^

ktnyt/chainer,pfnet/chainer,ktnyt/chainer,chainer/chainer,hvy/chainer,okuta/chainer,jnishi/chainer,wkentaro/chainer,ktnyt/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,tkerola/chainer,okuta/chainer,jnishi/chainer,wkentaro/chainer,hvy/chainer,jnishi/chainer,keisuke-umezawa/chainer,okuta/chainer,niboshi/chainer,hvy/chainer,chainer/chainer,hvy/chainer,wkentaro/chainer,wkentaro/chainer,okuta/chainer,jnishi/chainer,chainer/chainer,ktnyt/chainer,niboshi/chainer,niboshi/chainer,keisuke-umezawa/chainer,niboshi/chainer,chainer/chainer