man,units: tmpfiles.d(5) cleanup

Condition for /lib (necessary for split /usr) was missing from the unit.

Some changes which were done in tmpfiles.d(5) were not carried over to
systemd-tmpfiles(1).

Also use markup where possible.
tmpfiles: introduce the concept of unsafe operations

Various operations done by systemd-tmpfiles may only be safely done at
boot (e.g. removal of X lockfiles in /tmp, creation of /run/nologin).
Other operations may be done at any point in time (e.g. setting the
ownership on /{run,var}/log/journal). This distinction is largely
orthogonal to the type of operation.

A new switch --unsafe is added, and operations which should only be
executed during bootup are marked with an exclamation mark in the
configuration files. systemd-tmpfiles.service is modified to use this
switch, and guards are added so it is hard to re-start it by mistake.

If we install a new version of systemd, we actually want to enforce
some changes to tmpfiles configuration immediately. This should now be
possible to do safely, so distribution packages can be modified to
execute the "safe" subset at package installation time.

/run/nologin creation is split out into a separate service, to make it
easy to override.

https://bugzilla.redhat.com/show_bug.cgi?id=1043212
https://bugzilla.redhat.com/show_bug.cgi?id=1045849
sleep-config: fix useless check for swapfile type

Since 0c6f1f4ea49 the check was useless, because the kernel will
ever only write "partition" or "file" there.

OTOH, it is possible that "\\040(deleted)" (escaped " (deleted)")
will be added for removed files. This should not happen, so add
a warning to detect those cases.
unit: include peer identity in description of per-connection socket-activated services
shared: fix getpeername_pretty() for AF_UNIX sockets
bus: be a bit more verbose when debug mode is on
bus: also write debug logs about messages we send
bus: set cookie_reply and update kdbus.h
bus: update kdbus.h
bus: conditionally set cookie_reply/timeout and update kdbus.h
bus: rename message "serial" to "cookie"

Even if the lower-leveld dbus1 protocol calls it "serial", let's expose
the word "cookie" for this instead, as this is what kdbus uses and since
it doesn't imply monotonicity the same way "serial" does.
man: document sd_bus_message_get_cookie()
man: add missing sd_bus_message_get_cookie man page fie
bus: add a bit of pure/const decorators
journalctl: remove unexpected behavior of journalctl -b

This flag shouldn't try and consume the following argument. It should
behave like every other flag which takes an optional argument when
parsed by getopt_long.
completion: don't offer completions for journalctl -b

Since this is a shortopt with an optional argument, assume the user
knows what they're doing. The longopts --boot and --this-boot will
continue to offer boot IDs as completions.
build-sys: the pure/const warning options are probably too much as default, but let's make it available via "autogen.sh a"
build-sys: minor fixes found with cppcheck
Revert "journalctl: remove unexpected behavior of journalctl -b"

This reverts commit cf5bccc2bb9569030cb04debbc4208aaca0fe5b4.

We should fix thinks properly if they aren't perfect, not just break
other things...
Revert "completion: don't offer completions for journalctl -b"

This reverts commit c756a6d57cdb678b702c68913dae3e11ff0427ae.