fixed build errors for gcc 4.6

Log.cpp

@@ -24,7 +24,11 @@ void LogMsg::Process()
 
 const std::string& Log::GetTimestamp ()
 {
+#if (__GNUC__ == 4) && (__GNUC_MINOR__ <= 6)	
+	auto ts = std::chrono::monotonic_clock::now ();	
+#else	
 	auto ts = std::chrono::steady_clock::now ();	
+#endif	
 	if (ts > m_LastTimestampUpdate + std::chrono::milliseconds (500)) // 0.5 second
 	{
 		m_LastTimestampUpdate = ts;

Log.h

@@ -50,7 +50,11 @@ class Log: public i2p::util::MsgQueue<LogMsg>
 		
 		std::ostream * m_LogStream;
 		std::string m_Timestamp;
+#if (__GNUC__ == 4) && (__GNUC_MINOR__ <= 6) // gcc 4.6
+		std::chrono::monotonic_clock::time_point m_LastTimestampUpdate;
+#else		
 		std::chrono::steady_clock::time_point m_LastTimestampUpdate;	
+#endif		
 };
 
 extern Log * g_Log;

NetDb.h

@@ -92,7 +92,7 @@ namespace data
 
 			Reseeder * m_Reseeder;
 
-			friend NetDbRequests; 
+			friend class NetDbRequests; 
 			NetDbRequests m_Requests;
 
 			static const char m_NetDbPath[];