When growing the state, also grow the seed array. Otherwise memory
that was not allocated will be accessed.
This necessitated refactoring state seed allocation from
ipf_state_soft_init() into a new common ipf_state_seed_alloc() function
as it is now also used by ipf_state_rehash() when changing the size of
the state hash table in addition to by ipf_state_soft_init() during
initialization.
According to Christos Zoulas <christos@NetBSD.org>:
The bug was encountered by a NetBSD vendor who's customer machines had
large ipfilter states. The bug was reliably triggered by resizing the
state variables using "ipf -T".