bpo-36097: Use only public C-API in the_xxsubinterpreters module (adding as necessary). (gh-12359)

diff --git a/Objects/object.c b/Objects/object.c
index cf5264b..b446d59 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -5,6 +5,7 @@
 #include "pycore_pystate.h"
 #include "pycore_context.h"
 #include "frameobject.h"
+#include "interpreteridobject.h"
 
 #ifdef __cplusplus
 extern "C" {
@@ -1806,6 +1807,7 @@
     INIT_TYPE(&PySeqIter_Type, "sequence iterator");
     INIT_TYPE(&PyCoro_Type, "coroutine");
     INIT_TYPE(&_PyCoroWrapper_Type, "coroutine wrapper");
+    INIT_TYPE(&_PyInterpreterID_Type, "interpreter ID");
     return _Py_INIT_OK();
 
 #undef INIT_TYPE