Fix broken get_by_name method

There was a typo introduced during previous refactorings.
Obviously the check should be done with the class_traits module.
This part of the code was untested so the error was not noticed.
Unit tests will follow soon.

Author: iMichka

pygccxml/declarations/smart_pointer_traits.py

@@ -17,7 +17,7 @@ class internal_type_traits(object):
     # TODO: add exists function
     @staticmethod
     def get_by_name(type_, name):
-        if class_declaration_traits.is_my_case(type_):
+        if class_traits.is_my_case(type_):
             cls = class_traits.declaration_class(type_)
             return type_traits.remove_declarated(
                 cls.typedef(name, recursive=False).decl_type)