Here we are doing no more than adding the value for Py_mod_multiple_interpreters and using it for stdlib modules.  We will start checking for it ingh-104206 (once PyInterpreterState.ceval.own_gil is added ingh-104204).

* main:pythongh-99113: Add PyInterpreterConfig.own_gil (pythongh-104204)pythongh-104146: Remove unused var 'parser_body_declarations' from clinic.py (python#104214)pythongh-99113: Add Py_MOD_PER_INTERPRETER_GIL_SUPPORTED (pythongh-104205)pythongh-104108: Add the Py_mod_multiple_interpreters Module Def Slot (pythongh-104148)pythongh-99113: Share the GIL via PyInterpreterState.ceval.gil (pythongh-104203)pythonGH-100479: Add `pathlib.PurePath.with_segments()` (pythonGH-103975)pythongh-69152: Add _proxy_response_headers attribute to HTTPConnection (python#26152)pythongh-103533: Use PEP 669 APIs for cprofile (pythonGH-103534)pythonGH-96803: Add three C-API functions to make _PyInterpreterFrame less opaque for users of PEP 523. (pythonGH-96849)

…4205)Here we are doing no more than adding the value for Py_mod_multiple_interpreters and using it for stdlib modules.  We will start checking for it inpythongh-104206 (once PyInterpreterState.ceval.own_gil is added inpythongh-104204).

We also add PyInterpreterState.ceval.own_gil to record if the interpreter actually has its own GIL.Note that for now we don't actually respect own_gil; all interpreters still share the one GIL.  However, PyInterpreterState.ceval.own_gil does reflect PyInterpreterConfig.own_gil.  That lie is a temporary one that we will fix when the GIL really becomes per-interpreter.