Issue #18408: Fix array_index(), handle getarrayitem() failure
Issue #18408: Fix array_tolist(), handle PyList_SetItem() failure
Issue #18408: Fix dict_repr(), don't call PyObject_Repr() with an exception set

PyObject_Repr() can removes the current exception. For example, module_repr()
calls PyErr_Clear() if calling loader.module_repr(mod) failed.
Issue #18488: _pysqlite_final_callback() should not clear the exception set by
the last call to the step() method of a user function
Issue #18408: PyEval_EvalFrameEx() and PyEval_CallObjectWithKeywords() now fail
with an assertion error if they are called with an exception set
(PyErr_Occurred()).

If these functions are called with an exception set, the exception may be
cleared and so the caller looses its exception.

Add also assertions to PyEval_CallObjectWithKeywords() and call_function() to
check if the function succeed with no exception set, or the function failed
with an exception set.
Issue #18408: Fix _pysqlite_fetch_one_row(), in debug mode, don't call
type_call() with an exception set
Issue #18408: PyObject_Str(), PyObject_Repr() and type_call() now fail with an
assertion error if they are called with an exception set (PyErr_Occurred()).

As PyEval_EvalFrameEx(), they may clear the current exception and so the caller
looses its exception.
Issue #18408: Fix PyInit__curses_panel(), handle import_curses() failure

Don't call PyErr_NewException() if an exception is set, or type_call() would
fail with an assertion error.
Fix a compiler warning on FreeBSD

Modules/python.c:40: warning: ISO C90 forbids mixed declarations and code
Issue #18408: Fix _elementtree.c, don't call Python function from an expat
handler if a Python exception is set
Issue #18501, #18408: Fix expat handlers in pyexpat, don't call Python
functions if a Python exception was raised
Fix posix_chflags(): return_value was uninitialized when follow_symlinks=False
whereas the fchmodat() function is not avaialble.
(Merge 3.3) Fix posix_chflags(): return_value was uninitialized when
follow_symlinks=False whereas the fchmodat() function is not avaialble.