Cleanup and first step to enhance cpu measurments

• Start enhancing cpu measurements, using a message queue to send cpu time and a dedicated thread to compute measures. Not yet used
• Fix gcc v>9 warnings when passing pointer to packed structures fields in a function call
• Use same number for source and destination ports in the new GTP implementation, allowing (for example) running 4G and 5G cores on one system. At the end, the NGU or S1U port parameter in config file is used for both source and destination parameter
• Enhance telnet server, possibly including a telnet client when running a softmodem, providing console commands (----telnetsrv.listenstdin option) NB: doc not yet updated as this is a step in an enhancement. telnet server doc needs modifications and a dedicated doc for cpu measurements has to be created