This pull request adds support for parsing the source language in both
DWARF and CodeView. Specifically,
- The `LVSourceLanguage` class is introduced to represent any supported
language by any of the debug info representations.
- Update `LVDWARFReader.cpp` and `LVCodeViewVisitor.cpp` to parse the
source language where it applies. Added a new `=Language` attribute;
`getAttributeLanguage()` is internally used to control whether this
information is being printed.
0f38c54c6f