bpo-36356: pymain_free() calls _PyRuntime_Finalize() (GH-12435)

Ensure that _PyRuntime_Finalize() is always call. This change fix a
few memory leaks when running "python3 -V".

Include/internal/pycore_pystate.h

@@ -184,6 +184,8 @@ PyAPI_FUNC(void) _PyRuntimeState_ReInitThreads(void);
    Return NULL on success, or return an error message on failure. */
 PyAPI_FUNC(_PyInitError) _PyRuntime_Initialize(void);
 
+PyAPI_FUNC(void) _PyRuntime_Finalize(void);
+
 #define _Py_CURRENTLY_FINALIZING(tstate) \
     (_PyRuntime.finalizing == tstate)
 

Modules/main.c

@@ -839,6 +839,7 @@ pymain_free(void)
     _PyPathConfig_ClearGlobal();
     _Py_ClearStandardStreamEncoding();
     _Py_ClearArgcArgv();
+    _PyRuntime_Finalize();
 }