task->signal->notify_count is only initialized if
task->signal->group_exit_task is not NULL.  Reorder a conditional so
that uninitialised memory is not used.  Found by Valgrind.
Signed-off-by: NSteve VanDeBogart <vandebo-lkml@nerdbox.net>
Signed-off-by: NIngo Molnar <mingo@elte.hu>