a2672250be
Uses the `TrackingOutputBuffer` to populate the new member `Mangled::m_demangled_info`. `m_demangled_info` is lazily popluated by `GetDemangledInfo`. To ensure `m_demangled` and `m_demangled_info` are in-sync we clear `m_demangled_info` anytime `m_demangled` is set/cleared. https://github.com/llvm/llvm-project/pull/131836