Conditionaly create int conversion functions.

Cython/Compiler/PyrexTypes.py

@@ -1375,6 +1375,7 @@ class CIntType(CNumericType):
     exception_value = -1
 
     def create_to_py_utility_code(self, env):
+        if type(self).to_py_function is None:
             self.to_py_function = "__Pyx_PyInt_to_py_" + self.specialization_name()
             env.use_utility_code(TempitaUtilityCode.load(
                 "CIntToPy", "TypeConversion.c",
@@ -1383,6 +1384,7 @@ class CIntType(CNumericType):
         return True
 
     def create_from_py_utility_code(self, env):
+        if type(self).from_py_function is None:
             self.from_py_function = "__Pyx_PyInt_from_py_" + self.specialization_name()
             env.use_utility_code(TempitaUtilityCode.load(
                 "CIntFromPy", "TypeConversion.c",