Replace "running" with "not started" and don't show the pid if the subprocess
didn't start yet.

Also, document SystemExit.code attribute explicitly.

Also, document SystemExit.code attribute explicitly.

Patch written by Ben Hoyt.

The usage of os.scandir() reduces the number of calls to os.stat().
Initial patch written by Ben Hoyt.

assert() are noop when NDEBUG is defined. We want the opposite.

The garbage in _crtInstalledToken was causing the IsCrtInstalled() function to return TRUE without actually checking anything. We now initialize the variable first.

to make it easy to test 32-bit and 64-bit builds in the same working tree.

Patch by Martin Panter.

Patch by Martin Panter.

the dirent structure (ex: OpenIndiana).

function -- a better and faster directory iterator". Patch written by Ben
Hoyt.

Patch by Sayan Chowdhury.

not as stringified enum.  Patch by Demian Brecht.

raise a SystemError if a function returns a result and raises an exception.
The SystemError is chained to the previous exception.

Refactor also PyObject_Call() and PyCFunction_Call() to make them more readable.

Remove some checks which became useless (duplicate checks).

Change reviewed by Serhiy Storchaka.