Tickets 34-38 - coverity 13179-13183 - Dereference before NULL check
    
    https://fedorahosted.org/nunc-stans/ticket/34
    https://fedorahosted.org/nunc-stans/ticket/35
    https://fedorahosted.org/nunc-stans/ticket/36
    https://fedorahosted.org/nunc-stans/ticket/37
    https://fedorahosted.org/nunc-stans/ticket/38
    Reviewed by: mreynolds (Thanks!)
    Branch: master
    Fix Description: If job is passed to an ns_add job func, init job
    to NULL.  If the job alloc fails, return failure immediately.
    In ns_thrpool_destroy, tp->event_q_wakeup_job should never be NULL.
    Platforms tested: Fedora 21
    Flag Day: no
    Doc impact: no