pkg/54712: graphics/py-matplotlib is broken

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         54712
>Category:       pkg
>Synopsis:       graphics/py-matplotlib is broken
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Nov 23 08:40:00 +0000 2019
>Originator:     Andreas Gustafsson
>Release:        pkgsrc-current as of 2019-11-23
>Organization:

>Environment:
System: NetBSD 9.0_BETA
Architecture: x86_64
Machine: amd64
>Description:

After upgrading my NetBSD testbed host running 9.0_BETA/amd64 to
the current pkgsrc trunk, importing matplotlib.dates from
graphics/py-matplotlib fails with an undefined symbol:

  $ python3.7 -c 'import matplotlib.dates'
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
    File "/usr/pkg/lib/python3.7/site-packages/matplotlib/dates.py", line 159, in <module>
      import matplotlib.ticker as ticker
    File "/usr/pkg/lib/python3.7/site-packages/matplotlib/ticker.py", line 174, in <module>
      from matplotlib import transforms as mtransforms
    File "/usr/pkg/lib/python3.7/site-packages/matplotlib/transforms.py", line 43, in <module>
      from matplotlib._path import (
  ImportError: /usr/pkg/lib/python3.7/site-packages/matplotlib/_path.so: Undefined symbol "MPL_matplotlib_ft2font_ARRAY_API" (symnum = 140)

To rule out any local issue, I reproduced the problem using a freshly
installed NetBSD-current and equally freshly installed pkgsrc-current,
and it also failed, but with a different undefined symbol:

  $ python3.7 -c 'import matplotlib.dates'
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
    File "/usr/pkg/lib/python3.7/site-packages/matplotlib/dates.py", line 159, in <module>
      import matplotlib.ticker as ticker
    File "/usr/pkg/lib/python3.7/site-packages/matplotlib/ticker.py", line 174, in <module>
      from matplotlib import transforms as mtransforms
    File "/usr/pkg/lib/python3.7/site-packages/matplotlib/transforms.py", line 43, in <module>
      from matplotlib._path import (
  ImportError: /usr/pkg/lib/python3.7/site-packages/matplotlib/_path.so: Undefined symbol "MPL_matplotlib_backends__tkagg_ARRAY_API" (symnum = 27)

This issue is blocking me from generating further test reports
such as those at http://www.gson.org/netbsd/bugs/build/amd64-baremetal/.

>How-To-Repeat:

cd /usr/pkgsrc/graphics/py-matplotlib
make install
python3.7 -c 'import matplotlib.dates'

>Fix: