Sorry, I didn't want to push this change before the review :-( I was pushing a
change into the 2.7 branch.

* Move all functions to call objects in a new Objects/call.c file.
* Rename fast_function() to _PyFunction_FastCallKeywords().
* Copy null_error() from Objects/abstract.c
* Inline type_error() in call.c to not have to copy it, it was only
  called once.
* Export _PyEval_EvalCodeWithName() since it is now called
  from call.c.

is_size_t test was reversed. Bug spotted by INADA Naoki.

Issue #29507: Optimize slots calling Python methods. For Python methods, get
the unbound Python function and prepend arguments with self, rather than
calling the descriptor which creates a temporary PyMethodObject.

Add a new _PyObject_FastCall_Prepend() function used to call the unbound Python
method with self. It avoids the creation of a temporary tuple to pass
positional arguments.

Avoiding temporary PyMethodObject and avoiding temporary tuple makes Python
slots up to 1.46x faster. Microbenchmark on a __getitem__() method implemented
in Python:

Median +- std dev: 121 ns +- 5 ns -> 82.8 ns +- 1.0 ns: 1.46x faster (-31%)

Co-Authored-by: INADA Naoki <songofacandy@gmail.com>

Issue #29259, #29465: PyCFunction_Call() doesn't create anymore a redundant
tuple to pass positional arguments for METH_VARARGS.

Add a new cfunction_call() subfunction.

Issue #29306: Destroy argstuple and kwdict if Py_EnterRecursiveCall() fails.

* *PyCFunction_*Call*() functions now call Py_EnterRecursiveCall().
* PyObject_Call() now calls directly _PyFunction_FastCallDict() and
  PyCFunction_Call() to avoid calling Py_EnterRecursiveCall() twice per
  function call

_PyArg_NoPositional() now are macros.

Decreased density gives better collision statistics (average of 2.5 probes in a
full table versus 3.0 previously) and fewer occurences of starting a second
possibly overlapping sequence of 10 linear probes.  Makes resizes a little more
frequent but each with less work (fewer insertions and fewer collisions).