Remove dependency on dummy_threading (to solve a bootstrap problem).

Lib/functools.py

@@ -16,7 +16,10 @@ from collections import namedtuple
 try:
     from _thread import RLock
 except:
-    from dummy_threading import RLock
+    class RLock:
+        'Dummy reentrant lock'
+        def __enter__(self): pass
+        def __exit__(self, exctype, excinst, exctb): pass
 
 
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