search for an sscp-address and return ss7 instance in one go
By the current API definition, the user can limit the search range to a specific ss7 instance (if that instance is known). When the given ss7 instance pointer is NULL, the global list is searched. This scheme will be changed to:
When searching, always the global list is searched. If found, the address will be copied to the pointer which the caller has issued. We will also return the pointer to the ss7 instance. A returned NULL pointer indicates that the entry was not found. By creating a copy of the addressbook entry we also prevent that the caller might change the address data in the addressbook. The only legal way to change addressbook entries is the VTY.
The API should look like this:
struct osmo_ss7_instance *osmo_sccp_addr_by_name(const char *name, struct osmo_sccp_addr *dest);
const char *osmo_sccp_name_by_addr(const struct osmo_sccp_addr *addr);