Debugger doesn't correctly handle anonymous unions within structs/classes

[anevilyak]

While attempting to debug error messages relating to invalid DW_AT_specification attributes with programs generated by our newer gcc4, I'm running into issues digging into what's actually going on because Debugger isn't properly able to represent the AttributeValue class. The anonymous union is simply shown as a blank value node that expands to another instance of the AttributeValue class with the same blank value node ad infinitum. At the moment I'm not really clear as to what's going on though, since the same union declared outside of a class works fine. Attached a simplified test program which reproduces the issue.