title: makecython++ causes fatal error: Python.h: No such file or directory despite python3-dev installed
body: <p>My makefile:</p>
  
  <pre><code>SHELL := /bin/bash
  
  .PHONY: all
  all:
      pip install runcython
      makecython++ stitch_wrapper.pyx "" "stitch_rects.cpp ./hungarian/hungarian.cpp"
  
  hungarian: hungarian/hungarian.so
  
  hungarian/hungarian.so:
      cd hungarian &amp;&amp; \
      TF_INC=$$(python -c 'import tensorflow as tf; print(tf.sysconfig.get_include())') &amp;&amp; \
      if [ `uname` == Darwin ];\
      then g++ -std=c++11 -shared hungarian.cc -o hungarian.so -fPIC -I $$TF_INC -undefined dynamic_lookup;\
      else g++ -std=c++11 -shared hungarian.cc -o hungarian.so -fPIC -I  $$TF_INC; fi
  </code></pre>
  
  <p>I have already installed</p>
  
  <pre><code>-cython
  -runcython
  -python-dev
  -python3-dev
  -cffi
  </code></pre>
  
  <p>Unfortunately I continue to get the error:</p>
  
  <pre><code>pkg-config: command not found
  .cpp:4:20: fatal error: Python.h: No such file or directory
  compilation terminated.
  Makefile:5: recipe for target 'all' failed
  make: *** [all] Error 1
  </code></pre>