message: Use map::insert instead of try_emplace.
  try_emplace is C++17.
diff: @@ -136,7 +136,7 @@ void PdbIndex::BuildAddrToSymbolMap(CompilandIndexItem &cci) {
  // If the debug info is incorrect, we could have multiple symbols with the
  // same address. So use try_emplace instead of insert, and the first one
  // will win.
  - cci.m_symbols_by_va.try_emplace(va, PdbSymUid(cu_sym_id));
  + cci.m_symbols_by_va.insert(std::make_pair(va, PdbSymUid(cu_sym_id)));
  }
  }
  