Some attributes are not always found with castxml

[iMichka]

Sometimes attributes are not found. I tried various combinations and got very different results.
Gccxml was already not finding this attribute before.

This needs to be checked, but is not very critical now gccxml did not find it, so that nobody excepts it to be there.

https://github.com/gccxml/pygccxml/blob/develop/unittests/attributes_tester.py#L41

[iMichka]

Interestingly one of the tests if broken under Wily (castxml + Ubuntu 5.2.1-22ubuntu2).
That may help find out what is going on.

FAIL: test (attributes_tester.tester_t)

Traceback (most recent call last):
File "/home/popoff/repo/pygccxml/unittests/attributes_tester.py", line 44, in test
self.assertTrue((prefix + "(no throw)") == do_nothing.attributes)
AssertionError: False is not true

[iMichka]

The test was cleaned up. This works correctly with castxml (xml output version >= 1.137)