The timeouts in the networking library (DHCP lease timeouts and similar) should not be affected
by suspend. In the cases where CLOCK_BOOTTIME is not implemented, it is still safe to fallback to
CLOCK_MONOTONIC, as the consumers of the library (i.e., networkd) _should_ renew the leases when
coming out of suspend.
Feed a Router Advertisement to the code and expect proper events
each time. The sending part is ignored, as all of it is static code
in the real dhcp_network_icmp6_send_rs() function.
