Segmentation Fault with MuJoCo

I'm looking to benchmark both dm_control and MuJoCo.

This
```
import gym
from dm_control import suite
env = gym.make('HalfCheetah-v3')
```
yields
```
Traceback (most recent call last):
File "wrappers.pxi", line 1139, in mujoco_py.cymj.PyMjModel._extract_mj_names
AssertionError
Exception ignored in: 'mujoco_py.cymj.PyMjModel._set'
Traceback (most recent call last):
File "wrappers.pxi", line 1139, in mujoco_py.cymj.PyMjModel._extract_mj_names
AssertionError
Segmentation fault (core dumped)
```

whereas this exits gracefully:
```
import gym
env = gym.make('HalfCheetah-v3')
from dm_control import suite
env = gym.make('HalfCheetah-v3')
```
I'm using
```
dm-control 1.0.1
mujoco 2.1.3
mujoco-py 2.1.2.14
gym 0.21.0
```

While I'm happy to keep using this solution, it feels like a hack and a fix would be much appreciated!

首先，使用列出的 dm-control、MuJoCo、mujoco-py 和 gym 版本重现导入顺序差异。检查 wrappers.pxi 和 mujoco_py.cymj.PyMjModel._extract_mj_names 中报告的失败，然后验证在 gym.make 之前导入 dm_control 不再导致 assertion，随后出现 segmentation fault。

由索引模型根据 Issue 内容生成。