We not stopping the clients when networkd stops. They
should shut down cleanly and then we need to clean the DS.
One of requirements to implement
https://github.com/systemd/systemd/issues/10820.
```
^CBus bus-api-network: changing state RUNNING → CLOSED
DHCP SERVER: UNREF
DHCP SERVER: STOPPED
DHCP CLIENT (0x60943df0): STOPPED
veth-test: DHCP lease lost
veth-test: Removing address 192.168.5.31
NDISC: Stopping IPv6 Router Solicitation client
DHCP CLIENT (0x0): FREE
==24308==
==24308== HEAP SUMMARY:
==24308== in use at exit: 8,192 bytes in 2 blocks
==24308== total heap usage: 4,230 allocs, 4,228 frees, 1,209,732 bytes allocated
==24308==
==24308== LEAK SUMMARY:
==24308== definitely lost: 0 bytes in 0 blocks
==24308== indirectly lost: 0 bytes in 0 blocks
==24308== possibly lost: 0 bytes in 0 blocks
==24308== still reachable: 8,192 bytes in 2 blocks
==24308== suppressed: 0 bytes in 0 blocks
==24308== Rerun with --leak-check=full to see details of leaked memory
==24308==
==24308== For lists of detected and suppressed errors, rerun with: -s
==24308== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
==24308== could not unlink /tmp/vgdb-pipe-from-vgdb-to-24308-by-sus-on-Zeus
==24308== could not unlink /tmp/vgdb-pipe-to-vgdb-from-24308-by-sus-on-Zeus
==24308== could not unlink /tmp/vgdb-pipe-shared-mem-vgdb-24308-by-sus-on-Zeus
```
link_dirty(link);
}
-static int link_stop_clients(Link *link) {
+int link_stop_clients(Link *link) {
int r = 0, k;
assert(link);
int dhcp6_request_address(Link *link, int ir);
int dhcp6_lease_pd_prefix_lost(sd_dhcp6_client *client, Link* link);
+int link_stop_clients(Link *link);
+
const char* link_state_to_string(LinkState s) _const_;
LinkState link_state_from_string(const char *s) _pure_;
while ((link = hashmap_steal_first(m->links))) {
if (link->dhcp6_client)
(void) dhcp6_lease_pd_prefix_lost(link->dhcp6_client, link);
+
+ link_stop_clients(link);
+
link_unref(link);
}