Check event status in clWaitForEvents
Check event status in clWaitForEvents

As per the spec, this needs to return
CL_EXEC_STATUS_ERROR_FOR_EVENTS_IN_WAIT_LIST if any events in the wait
list have a negative status.

Oblomov/pocl,franz/pocl,rjodin/pocl,Oblomov/pocl,pocl/pocl,pocl/pocl,Oblomov/pocl,Oblomov/pocl,pocl/pocl,rjodin/pocl,rjodin/pocl,franz/pocl,franz/pocl,franz/pocl,franz/pocl,pocl/pocl,Oblomov/pocl,rjodin/pocl,pocl/pocl