cgls: fix running with -M option

systemd-machined doesn't store cgroup path in a state file anymore.
Let's figure it out from the scope.
nspawn: Fix erroneous OOM when building group list

change_uid_gid() never initialises sz which may cause greedy_realloc to
skip the initial buffer allocation.
sd-dhcp-client: test - fix for jenkins

This test should have been updated when changing the magic cookie handling around.

Reported by Ken MacLeod.
sd-rtnl: use GREEDY_REALLOC for message queues
sd-rtnl: don't drop multi-part messages

We still only return the first message part in callback/synchronous calls.
timedated: ignore initial delta in history data
bus: update kdbus.h
bus: catch up with kdbus changes (ABI break)
bash completion: add -i/--image to nspawn
sd-rtnl: use SO_PASSCRED

This unifies the socket handling with other sd-* libraries.
sd-dhcp-client: recevie_message - verify cmsg_len before reading
sd-dhcp-client: Add reference counting for DHCP

The DHCP library user can decide to free the DHCP client any time
the callback is called. After the callback has been called, other
computations may still be needed - the best example being a full
restart of the DHCP procedure in case of lease expiry.

Fix this by introducing proper reference counting. Properly handle
a returned NULL from the notify and stop functions if the DHCP
client was freed.
sd-dhcp-client: Add an explicit stop state for the DHCP client

Add an explicit stop state for the DHCP client so that the library
user can issue a stop at any time the callback has been called.
When returning from the callback, check also the stop state and
stop any further DHCP processing.
sd-ipv4ll: Add reference counting for IPv4LL

Similar to DHCP, the IPv4LL library user can decide to free the LL
client any time the callback is called. Guard against freeing the
LL client in the callback by introducing proper reference counting.

Also update code using the IPv4LL library to properly handle a
returned NULL from the notify and stop functions if the IPv4LL
client was freed.
sd-ipv4ll: Add an explicit stop state for IPv4LL

Add an explicit stop state for IPv4LL so that the user can stop the
IPv4LL client from the callback. When returning from the callback,
check also the stop state in order to halt any further protocol
processing.
sd-dhcp-client: rebind raw socket when resetting transaction id

As we are now filtering the raw socket based on the transaction id, we must
reset the BPF when we reset the transaction id.
sd-dhcp-client: assert that we can only create DISCOVER or REQUEST messages
sd-dhcp-client: document message creation a bit more

Also reshuffle some code to make the correspondence with the RFC a bit more
obvious.

Small functional change: fail if we try to send a message from the wrong state.
networkd: add an assert

This error should never happen, so replace the check with an assert. The check
was anyway broken due to an uninitialized return value.

Reported by Thomas Hindoe Paaboel Andersen <phomes@gmail.com>.
sd-dhcp-client: use client_initialiez and client_restart for REBOOT