DYNDNS: support for dualstack
When dyndns_iface option was not used, address of connection to LDAP
was used. This patch proposes following change:
* Interface containing address of connection is found.
* All A and AAAA addresses of this interface are collected.
* Collected addresses are sent during DDNS update.
* Function sss_iface_addr_add() is removed.
Resolves:
https://fedorahosted.org/sssd/ticket/2558