* bpo-35454: Fix miscellaneous minor issues in error handling.

* Fix a null pointer dereference.
(cherry picked from commit 8905fcc85a6fc3ac394bc89b0bbf40897e9497a6)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

(cherry picked from commit 0c1c4563a65ac451021d927058e4f25013934eb2)

Co-authored-by: INADA Naoki <methane@users.noreply.github.com>

Add two new private APIs: _PyObject_LookupAttr() and _PyObject_LookupAttrId()

* group the (stateful) runtime globals into various topical structs
* consolidate the topical structs under a single top-level _PyRuntimeState struct
* add a check-c-globals.py script that helps identify runtime globals

Other globals are excluded (see globals.txt and check-c-globals.py).

Replace
   _PyObject_CallArg1(func, arg)
with
   PyObject_CallFunctionObjArgs(func, arg, NULL)

Using the _PyObject_CallArg1() macro increases the usage of the C stack, which
was unexpected and unwanted. PyObject_CallFunctionObjArgs() doesn't have this
issue.

Replace
    PyObject_CallFunction(func, "O", arg)
and
    PyObject_CallFunction(func, "O", arg, NULL)
with
    _PyObject_CallArg1(func, arg)

Replace
    PyObject_CallFunction(func, NULL)
with
    _PyObject_CallNoArg(func)

_PyObject_CallNoArg() and _PyObject_CallArg1() are simpler and don't allocate
memory on the C stack.

UTF-8 represenatation of Unicode objects.

Since PyUnicodeDecodeError_GetObject() always returns bytes, following
PyBytes_AsString() can be replaced with PyBytes_AS_STRING().

This affects documentation, code comments, and a debugging messages.

Handle PyCapsule_Import() failure (exception) in PyCodec_NameReplaceErrors():
return immedialty NULL.