Closes GH-3023.

Pythran assumes shapes are shapes of long, whatever the underlying
architecture.

Currently Cython generates code like this:

     int __Pyx_InitCachedBuiltins(void) {
         __pyx_builtin_NAME = __Pyx_GetBuiltinName(...);
         if (!__pyx_builtin_NAME) __PYX_ERR(1, 44, __pyx_L1_error)
     }

     int __pyx_pymod_exec_MODULE(PyObject *__pyx_pyinit_module) {
         if (__Pyx_InitCachedBuiltins() < 0) __PYX_ERR(1, 1, __pyx_L1_error)
     }

When InitCachedBuiltins and InitCachedConstants call __PYX_ERR, they
pass the file and line where a builtin is used, but then pymod_exec
overwrites it with 1 and 1, and the error message looks like this:

       File "FILE", line 1, in init MODULE.
         import os
     NameError: name 'NAME' is not defined

After this change Cython generates:

     int __pyx_pymod_exec_MODULE(PyObject *__pyx_pyinit_module) {
         if (__Pyx_InitCachedBuiltins() < 0) goto __pyx_L1_error;
     }

and prints:

       File "FILE", line 44, in init MODULE.
         print(NAME)
     NameError: name 'NAME' is not defined

Fix a C compiler warning about an implicitly reduced integer range (Py_ssize_t -> int) when calling a helper function.
Closes GH-3028.

Closes GH-3031

* 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.