* master: (599 commits)
  Docs: Improved phrasing (pythonGH-14069)
  Remove redundant if check from optional argument function in argparse. (pythonGH-8766)
  bpo-37289: Add a test for if with ifexpr in the peephole optimiser to detect regressions (pythonGH-14127)
  Update What's New in Python 3.9 (pythonGH-14253)
  bpo-36511: Improve ARM32 buildbot scripts (pythonGH-14251)
  bpo-37151: remove _PyCFunction_FastCallDict (pythonGH-14269)
  Fix typo, 'widger' -> 'widget', in idlelib/tree.py (pythonGH-14263)
  Fix bpo number in News file. (pythonGH-14260)
  bpo-37342: Fix the incorrect nb_index's type in typeobj documentation (pythonGH-14241)
  Update What's New in Python 3.8 (pythonGH-14239)
  bpo-36710: Use tstate in pylifecycle.c (pythonGH-14249)
  Add missing single quote in io.TextIOWrapper.reconfigure documentation (pythonGH-14246)
  bpo-36511: Add buildbot scripts and fix tests for Windows ARM32 buildbot (pythonGH-13454)
  bpo-37333: Ensure IncludeTkinter has a value (pythonGH-14240)
  bpo-37331: Clarify format of socket handler messages in the documentation. (pythonGH-14234)
  bpo-37258: Not a bug, but added a unit test and updated documentation. (pythonGH-14229)
  bpo-36710: Remove PyImport_Cleanup() function (pythonGH-14221)
  Fix name of '\0'. (pythonGH-14222)
  bpo-36710: Add tstate parameter in import.c (pythonGH-14218)
  Document typing.ForwardRef (pythonGH-14216)
  ...

* Add 'tstate' parameter to many internal import.c functions.
* _PyImportZip_Init() now gets 'tstate' parameter rather than
  'interp'.
* Add 'interp' parameter to _PyState_ClearModules() and rename it
  to _PyInterpreterState_ClearModules().
* Move private _PyImport_FindBuiltin() to the internal C API; add
  'tstate' parameter to it.
* Remove private _PyImport_AddModuleObject() from the C API:
  use public PyImport_AddModuleObject() instead.
* Remove private _PyImport_FindExtensionObjectEx() from the C API:
  use private _PyImport_FindExtensionObject() instead.

* Add 'tstate' parameter to many internal import.c functions.
* _PyImportZip_Init() now gets 'tstate' parameter rather than
  'interp'.
* Add 'interp' parameter to _PyState_ClearModules() and rename it
  to _PyInterpreterState_ClearModules().
* Move private _PyImport_FindBuiltin() to the internal C API; add
  'tstate' parameter to it.
* Remove private _PyImport_AddModuleObject() from the C API:
  use public PyImport_AddModuleObject() instead.
* Remove private _PyImport_FindExtensionObjectEx() from the C API:
  use private _PyImport_FindExtensionObject() instead.