Issue #27809:

* PyObject_CallMethodObjArgs(), _PyObject_CallMethodIdObjArgs() and
  PyObject_CallFunctionObjArgs() now use fast call to avoid the creation of a
  temporary tuple
* Rename objargs_mktuple() to objargs_mkstack()
* objargs_mkstack() now stores objects in a C array using borrowed references,
  instead of storing arguments into a tuple

objargs_mkstack() uses a small buffer allocated on the C stack for 5 arguments
or less, or allocates a buffer in the heap memory.

Note: this change is different than the change 0e4f26083bbb, I fixed the test
to decide if the small stack can be used or not. sizeof(PyObject**) was also
replaced with sizeof(stack[0]) since the sizeof() was wrong (but gave the same
result).