Incorrect policy routing ip rule cleanup on reload with ip4table/ip6table change

[neocturne]

interface_change_config() changes the ip4table and ip6table fields of if_old here:

netifd/interface.c

Lines 1369 to 1370 in 777f594

	UPDATE(ip4table, reload_ip);
	UPDATE(ip6table, reload_ip);

. After the update, interface_ip_set_enabled(..., false) and interface_set_prefix_address() will clean up a number of implicitly created ip rules (set_ip_source_policy() and set_ip_lo_policy()) before setting them up again, but the cleanup will attempt to delete rules with the new ip[46]table instead of its old value, so the deletion fails. Only a full network restart will clean up rules properly.

I don't know the code well enough to propose a proper fix; the following ideas did not work out so far:

• Set interface_ip_set_enabled(..., false) before updating the fields (probably possible in the reload_ip == true case, unclear if the reload == true case can be made to work)
• Delete rule with 'unspecified' table lookup (there may be multiple rules that only differ by the table number)
• Store the table numbers used for the last rule creation in the interface_ip_settings, so the same table can be used for cleanup (possible for interface_ip_set_enabled(), looks more complicated for ``interface_set_prefix_address()`

It is unclear to me if a combination of the above ideas could be sufficient for a fix, or if more precise tracking of created rules would be required for cleanup.