* REF: make Utils dependency-free by moving search_include_directories to Main
* BUG: prefer sys.path before Cython/Include when searching for pxd files

CPython bpo-37221 reverts that backwards incompatible
change to the PyCode_New API, replacing it with a new
PyCode_NewWithPosOnlyArgs function.

The regex to match the gdb version is not intended to be interpreted as a regular string, it is designed to be used as-is as a regex.  This lets python know that minor detail.

And make it more flexible in terms of API change.

Current checks breaks when setting 0.10.0 as a Pythran version :-/

Closes GH-2976.

This was broken by the attempt to exclude C++ operations from true division.

Move the variable declarations in a C helper function to where they are actually used to avoid "unused" warnings in Py3.

This fixes Github issue #1950.

Fix compile error with 3.8

Closes GH-2936.

Closes GH-2939.

GH-2919: Prevent tuple constants that compare equal but have different item types from being merged into one.

At module cleanup time, clear the module dict before the global references that its content might still be using.

Keep owned references to builtins module, "cython_runtime" module and preimport module to prevent crashes when they get removed from sys.modules. Generate cleanup code for them in the end.
Closes #2885.