Do better cleaning in key_destroy() for VIMAGE case.

SPDB was cleaned using TAILQ_CONCAT() instead of calling key_unlink()
for each SP, thus we need to properly clean lists in each bucket of
V_sphashtbl to avoid panic in hashdestroy() when INVARIANTS is enabled.

Do the same for V_acqaddrhashtbl and V_acqseqhashtbl.

When we are called in DEFAULT_VNET, destroy also all global locks and
drain key_timer callout.

Reported by:	kp
Tested by:	kp