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.
use inferred NameNode type for builtin types instead of more generic entry type
fix some more potential C compiler warnings
fix (doc-)string usage in .pxd files
version bump
Type inference comments, enable test.
Remove use of symlink on Windows.
Avoid use of grep, ls on Windows
Merge branch 'master' into 0.20.x
Fix cdef class ordering in the presence of pxi includes.
Remove debugging.
Py3 test fixes
remove duplication of type analysis for base type tuple of Python classes (could crash the compiler for non-trivial base class expressions)
fix crash in Python object to C++ string conversion

--HG--
extra : amend_source : 6a5e7668208a89296264b05bbfe7640514318a1d
avoid generating lots of unused iteration fallback code for tuple unpacking
avoid unused fallback code also for typed list unpacking
fix non-CPython C compile problem (variable declaration after code)
Completely re-do out-of-order class declarations.
Merge branch '0.20.x'