Revert "explicitly set 'include' to numpy_incls (#18112)"

[jreback]

This reverts commit 54f2a5e.

xref #18112

our 2.7 wheels started breaking with this: https://travis-ci.org/MacPython/pandas-wheels/builds/302788535

[codecov]

Codecov Report

Merging #18365 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #18365      +/-   ##
==========================================
+ Coverage   91.36%   91.36%   +<.01%     
==========================================
  Files         164      164              
  Lines       49790    49790              
==========================================
+ Hits        45489    45492       +3     
+ Misses       4301     4298       -3

Flag	Coverage Δ
#multiple	89.17% <ø> (+0.02%)	⬆️
#single	39.53% <ø> (-0.07%)	⬇️

Impacted Files	Coverage Δ
pandas/io/gbq.py	25% <0%> (-58.34%)	⬇️
pandas/core/frame.py	97.8% <0%> (-0.1%)	⬇️
pandas/plotting/_converter.py	65.25% <0%> (+1.81%)	⬆️

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