Add use utility call for methods so that proto and impl are written to .c file

--HG--
extra : rebase_source : 3a3e0baf2718c57ca95a6e335d8c5950747e5945

Cython/Compiler/ExprNodes.py

@@ -3753,6 +3753,8 @@ class AttributeNode(ExprNode):
                 if entry.is_variable or entry.is_cmethod:
                     self.type = entry.type
                     self.member = entry.cname
+                    if entry.utility_code:
+                        env.use_utility_code(entry.utility_code)
                     return
                 else:
                     # If it's not a variable or C method, it must be a Python