firewall3: ipset: Handle reload_set properly

firewall3: ipset: Handle reload_set properly

The reload_set option was added in commit 509e673dab01 ("firewall3:
Improve ipset support"), and the purpose of the option is to control if
a set should be flushed or not on a firewall reload.

In some cases, the option unfortunately does not work properly. I had
fixed the errors locally, but failed to submit a v2 of "Improve ipset
support". This patch contains my local fixes, and after the following
changes are applied then the option (as well as ipset support) works as
at least I expect.

The following errors have been fixed:

* "family" was not written to the state file, causing all sets read from
this file was considered as ipv4. Save family to ensure that sets are
handled correctly on firewall reload.

* The default value of "reload_set" is false, meaning that the
reload-check in "fw3_create_ipsets()" is always true (on reload). A
consequence of this is that new sets are never created on firewall
reload. In order to ensure that new sets are created, only consider
"reload_set" if the set exists. If a set (from configuration) does not
exist, we always want to create it.

* On reload and before "fw3_destroy_ipsets()" are called, we need to
update run_state to ensure that sets are updated correctly. We need to
check if the sets in run_state is found in cfg_state, if not the set
should be destroyed (done by forcing reload_set to true). If the set is
found, then we copy the value of reload_set to the set in run_state so
that the elements are updated as the user expects.

Since we now always copy the value of reload_set from cfg_state, there
is no need to write reload_set to run_state.

Signed-off-by: Kristian Evensen <kristian.evensen@gmail.com>