journald: downgrade warning message when /dev/kmsg does not exist
journald: close /dev/kmsg again if we cannot make use of it
journald: before closing /dev/kmsg let's unregister the event source
bus-driverd: Fix return code in driver_request_name

RequestName return codes should be consistent with Dbus Specification.

VALUE - DESCRIPTION
1-The caller is now the primary owner of the name, replacing any previous owner,
2-The name already had an owner (QUEUE flag was not specified),
3-The name already has an owner (QUEUE flag was specified),
4-Application trying to request ownership of a name is already the owner of it.
bus: properly return an error code when release_name fails abnormally
journal-file.c: remove redundant assignment of variable

we also do 'last_index = (uint64_t) -1;' at the end of the while
loop so there is no reason to also do it here.
libsystemd-bus: true/false instead of yes/no in msg dump

Due to this patch, message dump (for message which includes boolean
type) is more consistent with dbus-send (which display true/false
instead of yes/no for boolean). It's only simple 'cosmetics change'.

** For dbus-send **

dbus-send --system --dest=org.freedesktop.DBus --type=method_call --print-reply / org.freedesktop.DBus.NameHasOwner string:org.freedesktop.login1

method return sender=org.freedesktop.DBus -> dest=:1.97 reply_serial=2
   boolean true

** For libsystemd-bus (without this patch) **

‣ Type=method_call  Endian=l  Flags=0  Version=2 Serial=8
  Destination=org.freedesktop.DBus  Path=/org/freedesktop/DBus  Interface=org.freedesktop.DBus  Member=NameHasOwner
  MESSAGE "s" {
  	STRING "org.freedesktop.login1";
  };

‣ Type=method_return  Endian=l  Flags=1  Version=2 Serial=51  ReplySerial=8
  Sender=:1.59  Destination=:1.67
  UniqueName=:1.59  WellKnownNames={org.freedesktop.DBus}
  MESSAGE "b" {
  	BOOLEAN yes;
  };

For me true/false seems to be better readable than yes/no for BOOLEAN.
update TODO
__thread --> thread_local for C11 compat

Also make thread_local available w/o including <threads.h>.
(as the latter hasn't been implemented, but this part is trivial)
util: no need for in_initrd() cache to be thread-local

the process only has one working directory, and a race is
harmless
_noreturn_ --> noreturn for C11 compat

also define noreturn w/o <stdnoreturn.h>
bus-util: return errors when encountered

Introduced in:
9f6eb1cd58f2ddf2eb6ba0e4de056e13d938af75
313333b403439360c0396a50d77d0a1ee2bca4df
networkd: rename link_update_flags to link_update

We are likely to track more than the flags in the future.
networkd: link - remove useless states

Rework the state-machine a bit.
networkd: bridge - fix state machine

We were entering BRIDGE_STATE_CREATED rather than BRIDGE_STATE_READY.