Parse more env vars in Py_Main():

* Add more options to _PyCoreConfig:

  * faulthandler
  * tracemalloc
  * importtime

* Move code to parse environment variables from _Py_InitializeCore()
  to Py_Main(). This change fixes a regression from Python 3.6:
  PYTHONUNBUFFERED is now read before calling pymain_init_stdio().
* _PyFaulthandler_Init() and _PyTraceMalloc_Init() now take an
  argument to decide if the module has to be enabled at startup.
* tracemalloc_start() is now responsible to check the maximum number
  of frames.

Other changes:

* Cleanup Py_Main():

  * Rename some pymain_xxx() subfunctions
  * Add pymain_run_python() subfunction

* Cleanup Py_NewInterpreter()
* _PyInterpreterState_Enable() now reports failure
* init_hash_secret() now considers pyurandom() failure as an "user
  error": don't fail with abort().
* pymain_optlist_append() and pymain_strdup() now sets err on memory
  allocation failure.

* Don't use "Python runtime" anymore to parse command line options or
  to get environment variables: pymain_init() is now a strict
  separation.
* Use an error message rather than "crashing" directly with
  Py_FatalError(). Limit the number of calls to Py_FatalError(). It
  prepares the code to handle errors more nicely later.
* Warnings options (-W, PYTHONWARNINGS) and "XOptions" (-X) are now
  only added to the sys module once Python core is properly
  initialized.
* _PyMain is now the well identified owner of some important strings
  like: warnings options, XOptions, and the "program name". The
  program name string is now properly freed at exit.
  pymain_free() is now responsible to free the "command" string.
* Rename most methods in Modules/main.c to use a "pymain_" prefix to
  avoid conflits and ease debug.
* Replace _Py_CommandLineDetails_INIT with memset(0)
* Reorder a lot of code to fix the initialization ordering. For
  example, initializing standard streams now comes before parsing
  PYTHONWARNINGS.
* Py_Main() now handles errors when adding warnings options and
  XOptions.
* Add _PyMem_GetDefaultRawAllocator() private function.
* Cleanup _PyMem_Initialize(): remove useless global constants: move
  them into _PyMem_Initialize().
* Call _PyRuntime_Initialize() as soon as possible:
  _PyRuntime_Initialize() now returns an error message on failure.
* Add _PyInitError structure and following macros:

  * _Py_INIT_OK()
  * _Py_INIT_ERR(msg)
  * _Py_INIT_USER_ERR(msg): "user" error, don't abort() in that case
  * _Py_INIT_FAILED(err)

* bpo-32025: Add time.thread_time()

* Add missing #endif

* Add NEWS blurb

* Add docs and whatsnew

* Address review comments

* Review comments

bpo-32011: Revert "Issue #15480: Remove the deprecated and unused TYPE_INT64 code from marshal." (#4381)

Simplify the reverted code.

This reverts commit e9bbe8b8.

* Setting sys.tracebacklimit to 0 or less now suppresses printing tracebacks.
* Setting sys.tracebacklimit to None now causes using the default limit.
* Setting sys.tracebacklimit to an integer larger than LONG_MAX now means using
  the limit LONG_MAX rather than the default limit.
* Fixed integer overflows in the case of more than 2**31 traceback items on
  Windows.
* Fixed output errors handling.

* bpo-32015: Asyncio cycling during simultaneously socket read/write and reconnection

* Tests fix

* Tests fix

* News add

* Add new unit tests

* bpo-16055: Fixes incorrect error text for int('1', base=1000)

* bpo-16055: Address review comments

in int(), float() and complex() parsers.

This also speeds up parsing non-ASCII numbers by around 20%.

Darwin may not require libm, but it doesn't hurt to link it and simplifies configuration logic.

Access to mkfifo(), mknod() and hard link creation is controled
by SELinux on Android.
Also remove test.support.android_not_root.

It can be removed after https://github.com/python/peps/commit/c28890fb421c906241da6da718f9eacc5a3109ee

Silence only expected AttributeError.

Silence only AttributeError when get "key" and "items" attributes in
the constructor and the update() method of dict and OrderedDict .

Get rid of _PyObject_HasAttrId() and PyDict_GetItemString().
Silence only expected AttributeError, KeyError and ImportError when
get an attribute, look up in a dict or import a module.

The openfp functions of aifp, sunau, and wave had pointed to the open
function of each module since 1993 as a matter of backwards
compatibility. In the case of aifc.openfp, it was both undocumented
and untested. This change begins the formal deprecation of those
openfp functions, with their removal coming in 3.9.

This additionally adds a TODO in test_pyclbr around using aifc.openfp,
though it shouldn't be changed until removal in 3.9.