ValueError: module functions cannot set METH_CLASS or METH_STATIC
#### Code Sample, a copy-pastable example if possible

```python
import matplotlib.pyplot as plt
import pandas as pd
```
#### Problem description

If I import pyplot before pandas, I get the following error:

```
Traceback (most recent call last):
  File "bug_pandas.py", line 2, in <module>
    import pandas as pd
  File "/home/joh/.local/lib/python3.6/site-packages/pandas/__init__.py", line 57, in <module>
    from pandas.io.api import *
  File "/home/joh/.local/lib/python3.6/site-packages/pandas/io/api.py", line 19, in <module>
    from pandas.io.packers import read_msgpack, to_msgpack
  File "/home/joh/.local/lib/python3.6/site-packages/pandas/io/packers.py", line 69, in <module>
    from pandas.util._move import (
ValueError: module functions cannot set METH_CLASS or METH_STATIC
```

If I re-order the imports so that pandas is imported first, the error disappears. Not sure if this is an issue with pyplot or pandas, but the exception seems to come from within pandas.

#### Expected Output

#### Output of ``pd.show_versions()``

<details>
INSTALLED VERSIONS
------------------
commit: None
python: 3.6.6.final.0
python-bits: 64
OS: Linux
OS-release: 4.18.8-041808-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: en_US.UTF-8
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.23.4
pytest: 3.8.0
pip: 9.0.1
setuptools: 40.4.3
Cython: None
numpy: 1.15.2
scipy: 0.19.1
pyarrow: None
xarray: None
IPython: 5.5.0
sphinx: 1.6.7
patsy: None
dateutil: 2.7.3
pytz: 2018.5
blosc: None
bottleneck: 1.2.0
tables: 3.4.2
numexpr: 2.6.4
feather: None
matplotlib: 2.1.1
openpyxl: 2.4.9
xlrd: 1.1.0
xlwt: None
xlsxwriter: None
lxml: 4.2.1
bs4: 4.6.0
html5lib: 0.999999999
sqlalchemy: 1.1.11
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None
</details>
