Introduce no-thread mode in ITTI

Introduce a --no-itti-threads command line option to disable threading
in ITTI, and call message handlers in the current thread. This is being
introduced in order to increase repeatability when testing the nrUE with
the IQPlayer. Without this feature, runs with the IQPlayer will end up
differently, depending on the timing of ITTI threads, mostly when
sending messages to RRC and NAS.

common/utils/ocp_itti/intertask_interface.h

@@ -484,9 +484,11 @@ void itti_poll_msg(task_id_t task_id, MessageDef **received_msg);
    \param args_p Optional argument to pass to the start routine
    @returns -1 on failure, 0 otherwise
  **/
-int itti_create_task(task_id_t task_id,
-                     void *(*start_routine) (void *),
-                     void *args_p);
+typedef struct {
+  void *args_to_start_routine;
+  void *(*shortcut_func)(void *);
+} ittiTask_parms_t;
+int itti_create_task(const task_id_t task_id, void *(*start_routine)(void *), const ittiTask_parms_t *args_p);
 
 int itti_create_queue(const task_info_t *task_info);