Reimplement itti_wait_tasks_end() to allow custom wait handlers

In the UE, we wish to handle ^C in the UE to send a message before
terminating, so we allow custom wait handlers to implement such
functionality. Use itti_wait_tasks_unblock() to unblock
itti_wait_tasks_end().

Also, implement itti_wait_tasks_end() using semaphores, as signals are
not async-signal-safe (and therefore should not be used in a signal
handler).

executables/lte-softmodem.c

@@ -614,7 +614,7 @@ int main ( int argc, char **argv )
   //getchar();
   if(IS_SOFTMODEM_DOSCOPE)
      load_softscope("enb",NULL);
-  itti_wait_tasks_end();
+  itti_wait_tasks_end(NULL);
 
 #if USING_GPROF
   // Save the gprof data now (rather than via atexit) in case we crash while shutting down

executables/lte-uesoftmodem.c

@@ -699,7 +699,7 @@ int main( int argc, char **argv ) {
   printf("TYPE <CTRL-C> TO TERMINATE\n");
   //getchar();
   printf("Entering ITTI signals handler\n");
-  itti_wait_tasks_end();
+  itti_wait_tasks_end(NULL);
   printf("Returned from ITTI signal handler\n");
   oai_exit=1;
   printf("oai_exit=%d\n",oai_exit);

executables/nr-cuup.c

@@ -153,7 +153,7 @@ int main(int argc, char **argv)
   itti_send_msg_to_task(TASK_CUUP_E1, 0, msg);
 
   printf("TYPE <CTRL-C> TO TERMINATE\n");
-  itti_wait_tasks_end();
+  itti_wait_tasks_end(NULL);
 
   logClean();
   printf("Bye.\n");

executables/nr-softmodem.c

@@ -733,7 +733,7 @@ int main( int argc, char **argv ) {
   // wait for end of program
   printf("Entering ITTI signals handler\n");
   printf("TYPE <CTRL-C> TO TERMINATE\n");
-  itti_wait_tasks_end();
+  itti_wait_tasks_end(NULL);
   printf("Returned from ITTI signal handler\n");
   oai_exit=1;
   printf("oai_exit=%d\n",oai_exit);

executables/nr-uesoftmodem.c

@@ -563,7 +563,7 @@ int main( int argc, char **argv ) {
   // wait for end of program
   printf("Entering ITTI signals handler\n");
   printf("TYPE <CTRL-C> TO TERMINATE\n");
-  itti_wait_tasks_end();
+  itti_wait_tasks_end(NULL);
   printf("Returned from ITTI signal handler\n");
   oai_exit=1;
   printf("oai_exit=%d\n",oai_exit);