patch 9.1.1239: if_python: no tuple data type support

Problem:  if_python: no tuple data type support (after v9.1.1232)
Solution: Add support for using Vim tuple in the python interface
          (Yegappan Lakshmanan)

closes: #16964

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/gc.c b/src/gc.c
index b95b2ca..c8aa5fa 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -439,6 +439,21 @@
 }
 
 /*
+ * Mark a tuple and its items with "copyID".
+ * Returns TRUE if setting references failed somehow.
+ */
+    int
+set_ref_in_tuple(tuple_T *tuple, int copyID)
+{
+    if (tuple != NULL && tuple->tv_copyID != copyID)
+    {
+	tuple->tv_copyID = copyID;
+	return set_ref_in_tuple_items(tuple, copyID, NULL, NULL);
+    }
+    return FALSE;
+}
+
+/*
  * Mark all lists and dicts referenced through tuple "t" with "copyID".
  * "ht_stack" is used to add hashtabs to be marked.  Can be NULL.
  *