netifd: Do not add local/source policy rules multiple times

netifd: Do not add local/source policy rules multiple times

interface_ip_set_enabled() is usually called two times right after one another,
once to handle config_ip and once to handle proto_ip. As long as
ip->iface->l3_dev.dev is set, the local/source policy rules are updated.

This value is in several cases set on both config_ip and proto_ip, causing the
rules to be added multiple time. The reason is that the kernel does not respect
the NLM_F_* flag for rules. In other words, the rule state has to be managed by
the routing daemon.

Since the local/source policy rules are bound to iface, this commit solves the
problem by adding a flag to interface which stores the current rule state. The
flag follows the enabled-paramter passed to interface_ip_set_enabled(), similar
to route-> and addr->enabled. The flag breaks the alignment of the interface
struct, but based on earlier commits this seems to be ok.

I have tested the patch in different configurations and have not found any
regression.

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