Remove warning for un-initialized enum return value.

Cython/Compiler/Nodes.py

@@ -1528,6 +1528,8 @@ class CEnumDefItemNode(StatNode):
             visibility = enum_entry.visibility, api = enum_entry.api,
             create_wrapper = enum_entry.create_wrapper)
         enum_entry.enum_values.append(entry)
+        if enum_entry.name:
+            enum_entry.type.values.append(entry.cname)
 
 
 class CTypeDefNode(StatNode):

Cython/Compiler/PyrexTypes.py

@@ -3617,6 +3617,10 @@ class CEnumType(CType):
             typecast(self, c_long_type, rhs),
             ' %s' % code.error_goto_if(error_condition or self.error_condition(result_code), error_pos))
 
+    @property
+    def default_value(self):
+        if self.values:
+            return self.values[0]
 
 class CTupleType(CType):
     # components [PyrexType]