Revert "pyximport: parse distutils config files (except local setup.cfg)"

This reverts commit 813ff05a80cef908704488e660fa07d49feb8a92.

This was an accidentally applied twice.
use all distutils config files

It is very astonishing to a user, that pyximport uses a different
set of config files from the underlying distutils.
Merge pull request #228 from tecki/master

Use all distutils config files in pyximport