[net processing] Annotate m_headers_sync_timeout as guarded by g_msgproc_mutex

src/net_processing.cpp

@@ -420,7 +420,7 @@ struct CNodeState {
     //! Whether we've started headers synchronization with this peer.
     bool fSyncStarted{false};
     //! When to potentially disconnect peer for stalling headers download
-    std::chrono::microseconds m_headers_sync_timeout{0us};
+    std::chrono::microseconds m_headers_sync_timeout GUARDED_BY(NetEventsInterface::g_msgproc_mutex){0us};
     //! Since when we're stalling block download progress (in microseconds), or 0.
     std::chrono::microseconds m_stalling_since{0us};
     std::list<QueuedBlock> vBlocksInFlight;