Also try to clarify the find_spec() error message.

Patch by Xiang Zhang.

bootstrap files:
    Could not find platform dependent libraries <exec_prefix
    Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]
Patch by Xiang Zhang

Issue #26823.

Handle PyTuple_New(0) failure.

Issue #27128.

Issue #27128.

Issue #27128.

Issue #27128.

Issue #27128.

Issue #27128: import_name() now calls _PyObject_FastCall() to avoid the
creation of a temporary tuple.

Issue #27128: PyFile_WriteObject() now calls _PyObject_FastCall() to avoid the
creation of a temporary tuple.

Use _PyObject_FastCall() to avoid the creation of temporary tuple.

Issue #27128: keyobject_richcompare() now calls _PyObject_FastCall() using a
small stack allocated on the C stack to avoid a temporary tuple.

Issue #27128: calliter_iternext() now calls _PyObject_FastCall() to avoid a
temporary empty tuple.

Cleanup also the code to reduce the indentation level.

Issue #27128: slot_tp_iter() now calls _PyObject_FastCall() to avoid a
temporary empty tuple.

Issue #27128: slot_nb_bool() now calls _PyObject_FastCall() to avoid a
temporary empty tuple to call the slot function.

Use an error label to reduce the level of indentation.

slot_sq_item() now calls _PyObject_FastCall() to avoid the creation of a
temporary tuple of 1 item to pass the 'item' argument to the slot function.