Closes #22205: sys._debugmallocstats is a cpython specific feature, so

test_debugmallocstats should be marked as such. Patch written by Martin
Matusiak.

Lib/test/test_sys.py

@@ -657,6 +657,7 @@ class SysModuleTest(unittest.TestCase):
         self.assertEqual(sys.implementation.name,
                          sys.implementation.name.lower())
 
+    @test.support.cpython_only
     def test_debugmallocstats(self):
         # Test sys._debugmallocstats()
         from test.script_helper import assert_python_ok