Address review: use wrapper functions instead of low-level accessors

Use _Py_IsCoreInitialized() in preconfig.c and Py_IsInitialized() in
Py_InitializeEx(), removing the unnecessary runtime local variable.

Thanks picnixz!

Author: gpshead

Python/preconfig.c

@@ -928,7 +928,7 @@ _PyPreConfig_Write(const PyPreConfig *src_config)
         return status;
     }
 
-    if (_PyRuntimeState_GetCoreInitialized(&_PyRuntime)) {
+    if (_Py_IsCoreInitialized()) {
         /* bpo-34008: Calling this functions after Py_Initialize() ignores
            the new configuration. */
         return _PyStatus_OK();

Python/pylifecycle.c

@@ -1505,9 +1505,8 @@ Py_InitializeEx(int install_sigs)
     if (_PyStatus_EXCEPTION(status)) {
         Py_ExitStatusException(status);
     }
-    _PyRuntimeState *runtime = &_PyRuntime;
 
-    if (_PyRuntimeState_GetInitialized(runtime)) {
+    if (Py_IsInitialized()) {
         /* bpo-33932: Calling Py_Initialize() twice does nothing. */
         return;
     }