import torch_scatter import torch_scatter.scatter_cpu ImportError: libtorch_cpu.so

进入python3，遇到这个错误

```python
 import torch_scatter
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/dell/.local/lib/python3.6/site-packages/torch_scatter/__init__.py", line 3, in <module>
    from .mul import scatter_mul
  File "/home/dell/.local/lib/python3.6/site-packages/torch_scatter/mul.py", line 3, in <module>
    from torch_scatter.utils.ext import get_func
  File "/home/dell/.local/lib/python3.6/site-packages/torch_scatter/utils/ext.py", line 2, in <module>
    import torch_scatter.scatter_cpu
ImportError: libtorch_cpu.so: cannot open shared object file: No such file or directory

```