bpo-36818: Add PyInterpreterState.runtime field. (gh-13129)

https://bugs.python.org/issue36818
diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
index d5e40ef..099afd8 100644
--- a/Modules/_threadmodule.c
+++ b/Modules/_threadmodule.c
@@ -996,7 +996,7 @@
 
     tstate = boot->tstate;
     tstate->thread_id = PyThread_get_thread_ident();
-    _PyThreadState_Init(&_PyRuntime, tstate);
+    _PyThreadState_Init(tstate);
     PyEval_AcquireThread(tstate);
     tstate->interp->num_threads++;
     res = PyObject_Call(boot->func, boot->args, boot->keyw);