network: more asserts to shut up scan-build
loopback-setup: remove stray hunk
execute: also set SO_SNDBUF when spawning a service with stdout/stderr connected to journald
bus: let's use GREEDY_REALLOC() when allocating space for containers
bus: use GREEDY_REALLOC() when allocating message queues
bus: fix symlink to bus proxy socket
systemctl: properly initialize and free sd_bus_error in "systemctl cat"

We need to properly initialize all error structs before use and free
them after use.

Also, there's no point in flushing stdout if we output a \n anyway...
units: properly make bus proxy socket of type Accept=yes
bus: also mask dbus.service in generator if kdbus is found
bus: when a busname unit refuses to activate a service it should flush the queue
Add bus-driverd

systemd-bus-driverd is a small daemon that connects to kdbus and
implements the org.freedesktop.DBus interface. IOW, it provides the bus
functions  traditionally taken care for by dbus-daemon.

Calls are proxied to kdbus, either via libsystemd-bus (were applicable)
or with the open-coded use of ioctl().

Note that the implementation is not yet finished as the functions to
add and remove matches and to start services by name are still missing.
bus: fix typo in systemd-bus-proxyd
journal-file: protect against alloca(0)
core: always create /dev/kdbus/ns (and make it private 0700) after setting up the kdbus system bus
bus: when entering an existing namespace to connect to a container's system bus also switch over PID namespace

This is necessary to ensure that kdbus can collect creds of the
destination namespace when connecting.
build-sys: build bus-driverd if kdbus support is enabled
bus: when connecting to a container's system bus, double fork after joining the container's namespace

setns(CLONE_NEWPID) only applies to child processes, hence let's fork
once after joining the container's namespace.
bus: update kdbus.h
bus: use gperf to map error string to errno
man: reword awkward phrase