Patch by Tal Einat.

* Replace PyArg_ParseTupleAndKeywords() with _PyArg_ParseStackAndKeywords()
  which is more efficient to parse keywords, since it decodes only keywords
  (char*) from UTF-8 once, instead of decoding at each call.
* METH_FASTCALL avoids the creation of a temporary tuple to pass positional
  arguments.

Patch written by INADA Naoki, pushed by Victor Stinner.

Issue #29312.

Issue #29311: dict.get() and dict.setdefault() methods now use Argument Clinic
to parse arguments. Their calling convention changes from METH_VARARGS to
METH_FASTCALL which avoids the creation of a temporary tuple.

The signature of docstrings is also enhanced. For example,
    get(...)
becomes:
    get(self, key, default=None, /)

Issue #29259.

Issue #29259:

* Detect PyCFunction is the current frame, not only in the older frame
* Ignore PyCFunction_Call() since it now calls _PyCFunction_FastCallDict(), and
  _PyCFunction_FastCallDict() is already detected

Issue #29259: use a different case for METH_VARARGS and
METH_VARARGS|METH_KEYWORDS to avoid testing again flags to decide if keywords
should be checked or not.

Issue #29259.

Issue #29259. All other functions calling functions start with the similar
assertion.

Issue #29259. We had 3 versions of similar code:

* PyCFunction_Call()
* _PyCFunction_FastCallDict()
* _PyCFunction_FastCallKeywords()

PyCFunction_Call() now calls _PyCFunction_FastCallDict() to factorize the code.

Issue #29259:

* Move also the !PyErr_Occurred() assertion to the top, similar to
  other functions.
* Fix also comment/error messages: the function was renamed to
  _PyMethodDef_RawFastCallDict()

Issue #29259.

Issue ##27830, Issue #29259.

Issue #29259, #29263. methoddescr_call() creates a PyCFunction object, call it
and the destroy it. Add a new _PyMethodDef_RawFastCallDict() method to avoid
the temporary PyCFunction object.

Issue #29259.

in socket.sendto().  A PyErr_Occurred() check was happening later, but
it is better to just use the return value and not call PyErr_Occurred().