gh-102660: Handle m_copy Specially for the sys and builtins Modules (gh-102661)

It doesn't make sense to use multi-phase init for these modules. Using a per-interpreter "m_copy" (instead of PyModuleDef.m_base.m_copy) makes this work okay. (This came up while working on gh-101660.)

Note that we might instead end up disallowing re-load for sys/builtins since they are so special.

https://github.com/python/cpython/issues/102660

Include/internal/pycore_interp.h

@@ -111,6 +111,7 @@ struct _is {
 
     PyObject *dict;  /* Stores per-interpreter state */
 
+    PyObject *sysdict_copy;
     PyObject *builtins_copy;
     // Initialized to _PyEval_EvalFrameDefault().
     _PyFrameEvalFunction eval_frame;