Ensure alq's shutdown_pre_sync event handler is deregistered on module unload to avoid a dangling pointer and eventual panic on system shutdown.
Ensure alq's shutdown_pre_sync event handler is deregistered on module unload to
avoid a dangling pointer and eventual panic on system shutdown.

Reported by:	Ali <comnetboy at gmail.com>
Tested by:	Ali <comnetboy at gmail.com>
MFC after:	1 week

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