_collections._tuplegetter: make __init__ a builtin method as well

Author: cosminbasca

graalpython/lib-graalpython/_collections.py

@@ -59,6 +59,7 @@ def __reduce__(self):
 
 
 class _tuplegetter(object):
+    @__graalpython__.builtin_method
     def __init__(self, index, doc):
         self.index = index
         self.__doc__ = doc