gh-108634: Py_TRACE_REFS uses a hash table (#108663)

Python built with "configure --with-trace-refs" (tracing references)
is now ABI compatible with Python release build and debug build.
Moreover, it now also supports the Limited API.

Change Py_TRACE_REFS build:

* Remove _PyObject_EXTRA_INIT macro.
* The PyObject structure no longer has two extra members (_ob_prev
  and _ob_next).
* Use a hash table (_Py_hashtable_t) to trace references (all
  objects): PyInterpreterState.object_state.refchain.
* Py_TRACE_REFS build is now ABI compatible with release build and
  debug build.
* Limited C API extensions can now be built with Py_TRACE_REFS:
  xxlimited, xxlimited_35, _testclinic_limited.
* No longer rename PyModule_Create2() and PyModule_FromDefAndSpec2()
  functions to PyModule_Create2TraceRefs() and
  PyModule_FromDefAndSpec2TraceRefs().
* _Py_PrintReferenceAddresses() is now called before
  finalize_interp_delete() which deletes the refchain hash table.
* test_tracemalloc find_trace() now also filters by size to ignore
  the memory allocated by _PyRefchain_Trace().

Test changes for Py_TRACE_REFS:

* Add test.support.Py_TRACE_REFS constant.
* Add test_sys.test_getobjects() to test sys.getobjects() function.
* test_exceptions skips test_recursion_normalizing_with_no_memory()
  and test_memory_error_in_PyErr_PrintEx() if Python is built with
  Py_TRACE_REFS.
* test_repl skips test_no_memory().
* test_capi skisp test_set_nomemory().

1 files changed, 4 insertions, 0 deletions

diff --git a/Lib/test/test_repl.py b/Lib/test/test_repl.py
index ddb4aa6..58392f2 100644
--- a/Lib/test/test_repl.py
+++ b/Lib/test/test_repl.py
@@ -5,6 +5,7 @@ import os
 import unittest
 import subprocess
 from textwrap import dedent
+from test import support
 from test.support import cpython_only, has_subprocess_support, SuppressCrashReport
 from test.support.script_helper import kill_python
 
@@ -59,6 +60,9 @@ def run_on_interactive_mode(source):
 class TestInteractiveInterpreter(unittest.TestCase):
 
     @cpython_only
+    # Python built with Py_TRACE_REFS fail with a fatal error in
+    # _PyRefchain_Trace() on memory allocation error.
+    @unittest.skipIf(support.Py_TRACE_REFS, 'cannot test Py_TRACE_REFS build')
     def test_no_memory(self):
         # Issue #30696: Fix the interactive interpreter looping endlessly when
         # no memory. Check also that the fix does not break the interactive