Closes #18272: use 'builtins' for 3.3 instead of __builtin__

Doc/library/imp.rst

@@ -158,7 +158,7 @@ This module provides an interface to the mechanisms used to implement the
           cache = {}
 
    It is legal though generally not very useful to reload built-in or dynamically
-   loaded modules, except for :mod:`sys`, :mod:`__main__` and :mod:`__builtin__`.
+   loaded modules, except for :mod:`sys`, :mod:`__main__` and :mod:`builtins`.
    In many cases, however, extension modules are not designed to be initialized
    more than once, and may fail in arbitrary ways when reloaded.
 

Doc/library/itertools.rst

@@ -762,7 +762,7 @@ which incur interpreter overhead.
        """ Call a function repeatedly until an exception is raised.
 
        Converts a call-until-exception interface to an iterator interface.
-       Like __builtin__.iter(func, sentinel) but uses an exception instead
+       Like builtins.iter(func, sentinel) but uses an exception instead
        of a sentinel to end the loop.
 
        Examples: