machine: generalise logic GetMachineAddresses to later use it in varlink interface

src/shared/local-addresses.c

@@ -104,7 +104,7 @@ static int add_local_address_full(
         return 1;
 }
 
-static int add_local_address(
+int add_local_address(
                 struct local_address **list,
                 size_t *n_list,
                 int ifindex,

src/shared/local-addresses.h

@@ -16,6 +16,8 @@ struct local_address {
 
 bool has_local_address(const struct local_address *addresses, size_t n_addresses, const struct local_address *needle);
 
+int add_local_address(struct local_address **list, size_t *n_list, int ifindex, unsigned char scope, int family, const union in_addr_union *address);
+
 int local_addresses(sd_netlink *rtnl, int ifindex, int af, struct local_address **ret);
 
 int local_gateways(sd_netlink *rtnl, int ifindex, int af, struct local_address **ret);