Debugger: Improve caching of unnamed structures

Task-number: QTCREATORBUG-9947

Cherry-picked from 16c4c2ae649221c1a18dd38bfd6cda0585356319

Change-Id: I901bb87ecafc4c1260003de51678ab66122aaffa
Reviewed-by: Mitch Curtis <mitch.curtis@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
Reviewed-by: David Schulz <david.schulz@digia.com>
Reviewed-by: hjk <hjk121@nokiamail.com>
Debugger: Implement dumper for std::unordered_{set,map}

Task-number: QTCREATORBUG-9855

Change-Id: I985745530d93e1c191442431a7a9449a1c4c059a
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: David Schulz <david.schulz@digia.com>