alq, siftr: add panic/debugger checks to shutdown hooks

[mhorne]

Summary

Don't try to gracefully terminate the pkt_manager thread if the
scheduler is not running.

We should not attempt to shutdown ald if RB_NOSYNC is set, and must not
if the scheduler is stopped (the function calls wakeup()).

[markj]

Yes I don't think these handlers will work properly in panic context.

We should not attempt to shutdown ald if RB_NOSYNC is set

ald -> alq