Issue 2186 and 2187.  Move filter from itertools to builtins.
diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
index 4e0902b..13dc1f9 100644
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -8,6 +8,7 @@
 from functools import reduce
 maxsize = test_support.MAX_Py_ssize_t
 minsize = -maxsize-1
+ifilter = filter
 
 def lzip(*args):
     return list(zip(*args))