Remove check for matching the rulenum, ruleid and rule pointer from
dyn_lookup_ipv[46]_state_locked(). These checks are remnants of not
ready to be committed code, and they are there by accident.
Due to the race these checks can lead to creating of duplicate states
when concurrent threads in the same time will try to add state for two
packets of the same flow, but in reverse directions and matched by
different parent rules.

Reported by:	lev

Restore the ability to keep states after parent rule deletion.

This feature is disabled by default and was removed when dynamic states
implementation changed to be lockless. Now it is reimplemented with small
differences - when dyn_keep_states sysctl variable is enabled,
dyn_match_ipv[46]_state() function doesn't match child states of deleted
rule. And thus they are keept alive until expired. ipfw_dyn_lookup_state()
function does check that state was not orphaned, and if so, it returns
pointer to default_rule and its position in the rules map. The main visible
difference is that orphaned states still have the same rule number that
they have before parent rule deleted, because now a state has many fields
related to rule and changing them all atomically to point to default_rule
seems hard enough.

Reported by:	<lantw44 at gmail.com>