Issue #9828: Destroy the GIL in Py_Finalize(), so that it gets properly

re-created on a subsequent call to Py_Initialize().  The problem (a crash)
wouldn't appear in 3.1 or 2.7 where the GIL's structure is more trivial.

Python/pythonrun.c

@@ -514,6 +514,10 @@ Py_Finalize(void)
 
     PyGrammar_RemoveAccelerators(&_PyParser_Grammar);
 
+#ifdef WITH_THREAD
+    _PyEval_FiniThreads();
+#endif
+
 #ifdef Py_TRACE_REFS
     /* Display addresses (& refcnts) of all objects still alive.
      * An address can be used to find the repr of the object, printed