localectl: fix localectl set-x11-keymap syntax description

This complements the fix in:

    commit cd4c6fb12598435fe24431f1dd616f9582f0e3bd
    Author: Jan Synacek <jsynacek@redhat.com>
    Date:   Mon Oct 20 12:43:39 2014 +0200

        man: fix localectl set-x11-keymap syntax description
Properly define the __NR_memfd_create macro for MIPS

This macro exists for MIPS since v3.17:
  https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=42944521af97a3b25516f15f3149aec3779656dc
util: introduce negative_errno()

Imagine a constructor like this:

        int object_new(void **out) {
                void *my_object;
                int r;

                ...
                r = ioctl(...);
                if (r < 0)
                        return -errno;
                ...

                *out = my_object;
                return 0;
        }

We have a lot of those in systemd. If you now call those, gcc might inline
the call and optimize it. However, gcc cannot know that "errno" is
negative if "r" is. Therefore, a caller like this will produce warnings:

        r = object_new(&obj);
        if (r < 0)
                return r;

        obj->xyz = "foobar";

In case the ioctl in the constructor fails, gcc might assume "errno" is 0
and thus the error-handling is not triggered. Therefore, "obj" is
uninitialized, but accessed. Gcc will warn about that.

The new negative_errno() helper can be used to mitigate those warnings.
The helper is guaranteed to return a negative integer. Furthermore, it
spills out runtime warnings if "errno" is non-negative.

Instead of returning "-errno", you can use:
        return negative_errno();

gcc will no longer assume that this can return >=0, thus, it will not warn
about it.

Use this new helper in libsystemd-terminal to fix some grdev-drm warnings.
barrier: explicitly ignore return values of barrier_place()

The barrier implementation tracks remote states internally. There is no
need to check the return value of any barrier_*() function if the caller
is not interested in the result. The barrier helpers only return the state
of the remote side, which is usually not interesting as later calls to
barrier_sync() will catch this, anyway.

Shut up coverity by explicitly ignoring return values of barrier_place()
if we're not interested in it.
sd-bus: sync kdbus.h (ABI break)

Catch up with some changes in kdbus.h:

  * KDBUS_{ITEM,ATTACH}_CONN_NAME were renamed to
    KDBUS_{ITEM,ATTACH}_CONN_DESCRIPTION, so the term 'name' is not
    overloaded as much.

  * The item types were re-ordered a little so they are lined up to the
    order of the corresponding KDBUS_ATTACH flags

  * A new item type KDBUS_ITEM_OWNED_NAME was introduced, designated to
    store a struct kdbus_name in item->name. KDBUS_ITEM_NAME soley
    stores data in item->str now

  * Some kerneldoc fixes
sd-bus: rename "connection name" to "description" for the sd-bus API too

kdbus recently renamed this concept, and so should we in what we expose
in userspace.
test: use assert_se in test_hashmap_move
sd-event: rename sd_event_source_set_name() to sd_event_source_get_name()

To mirror the recent name change of the concept for sd_bus objects,
follow the same logic for sd_event_source objects, too.
sd-event: implicitly set signal event source's descriptions to the signal name
sd-bus: also allow setting descriptions on bus slots
sd-bus: make use of free_and_strdup() where it makes sense
sd-bus,sd-event: unify error handling of object descriptions

a) When getting the description return ENXIO if none is set

b) Allow setting a description to NULL

c) return ECHILD on fork() like for other calls
sd-bus: rename sd_bus_get_server_id() to sd_bus_get_owner_id()

In kdbus a "server id" is mostly a misnomer, as there isn't any "server"
involved anymore. Let's rename this to "owner" id hence, since it is an
ID that is picked by the owner of a bus or direct connection. This
matches nicely the sd_bus_get_owner_creds() call we already have.
update TODO
update TODO
util: when sealing memfds, also use F_SEAL_SEAL

Let's be strict here, since its better to be safe than sorry.
TODO: update
man/tmpfiles.d: fix typo
units: make systemd-journald.service Type=notify

It already calls sd_notify(), so it looks like an oversight.

Without it, its ordering to systemd-journal-flush.service is
non-deterministic and the SIGUSR1 from flushing may kill journald before
it has its signal handlers set up.

https://bugs.freedesktop.org/show_bug.cgi?id=85871
https://bugzilla.redhat.com/show_bug.cgi?id=1159641
buildsys: test-util needs -lm for fabs()