Catch failure of lfds611_queue_enqueue and exit in this case.

This may have an impact on the behavior of the whole system
but I think it's better to exit than to be silent.


git-svn-id: http://svn.eurecom.fr/openair4G/trunk@7787 818b1a75-f10b-46b9-bf7c-635c3b92a50f