bpo-34567: pythoninfo gets coreconfig (GH-9043)

* Add _testcapi.get_coreconfig() to get the _PyCoreConfig of the
  interpreter
* test.pythoninfo now gets the core configuration using
  _testcapi.get_coreconfig()
diff --git a/Modules/main.c b/Modules/main.c
index 974a0a6..6f817b6 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -1018,8 +1018,8 @@
 }
 
 
-static PyObject*
-wstrlist_as_pylist(int len, wchar_t **list)
+PyObject*
+_Py_wstrlist_as_pylist(int len, wchar_t **list)
 {
     assert(list != NULL || len < 1);
 
@@ -1502,7 +1502,7 @@
 #define COPY_WSTRLIST(ATTR, LEN, LIST) \
     do { \
         if (ATTR == NULL) { \
-            ATTR = wstrlist_as_pylist(LEN, LIST); \
+            ATTR = _Py_wstrlist_as_pylist(LEN, LIST); \
             if (ATTR == NULL) { \
                 return _Py_INIT_NO_MEMORY(); \
             } \