Move CaptureMessageToFile() declaration from header to implementation

src/net.cpp

@@ -2915,10 +2915,11 @@ uint64_t CConnman::CalculateKeyedNetGroup(const CAddress& address) const
     return GetDeterministicRandomizer(RANDOMIZER_ID_NETGROUP).Write(vchNetGroup.data(), vchNetGroup.size()).Finalize();
 }
 
-void CaptureMessageToFile(const CAddress& addr,
-                          const std::string& msg_type,
-                          Span<const unsigned char> data,
-                          bool is_incoming)
+// Dump binary message to file, with timestamp.
+static void CaptureMessageToFile(const CAddress& addr,
+                                 const std::string& msg_type,
+                                 Span<const unsigned char> data,
+                                 bool is_incoming)
 {
     // Note: This function captures the message at the time of processing,
     // not at socket receive/send time.

src/net.h

@@ -1221,12 +1221,6 @@ private:
     friend struct ConnmanTestMsg;
 };
 
-/** Dump binary message to file, with timestamp */
-void CaptureMessageToFile(const CAddress& addr,
-                          const std::string& msg_type,
-                          Span<const unsigned char> data,
-                          bool is_incoming);
-
 /** Defaults to `CaptureMessageToFile()`, but can be overridden by unit tests. */
 extern std::function<void(const CAddress& addr,
                           const std::string& msg_type,