sd-bus: sync kdbus.h (ABI break)

The KDBUS_CMD_FREE ioctl now uses a struct rather than a direct pointer
to the offset to free.

The KDBUS_CMD_MSG_CANCEL ioctl has also changes, but there's no user of
it yet in systemd.
sd-bus: remove unused variable

It is no longer used after d663f1b1a92a778bcdc68f29b8c08cb49431b4f7
keymap: Fix touchpad toggle on Toshiba Satellite P75-A7200

Just like everywhere else we use KEY_F21 instead of KEY_TOUCHPAD_TOGGLE for X
friendliness.
keymap: Fix touchpad toggle key on Asus laptops

https://launchpad.net/bugs/1377352
sd-bus: fix use-after-free in close_kdbus_msg()

Walk the items first, then free the memory of the message.

Also, while at it, make coverity happy with an explicit (void) prefix.
We intentionally ignore the return value here.
sd-bus: fix KDBUS_CMD_FREE user

Fix a user of the KDBUS_CMD_FREE ioctl that was missed in the transition.
sd-bus: check return value of vasprintf

Check for OOM situations when vasprintf() returns < 0 in bus_error_setfv().

Spotted by coverity.
bus-proxyd: check return values of getpeercred() and getpeersec()

If we can't get the remote peer or security creds, bail out.

Spotted by coverity.
man: move commandline parsing to a separate section

It is very long already, and obscures the description of
ExecStart, and it is about to get longer.
man: document stripping of quotes
Update TODO
/proc/sys prefixes are not necessary for sysctl anymore
bus-proxyd: assorted cleanups and fixes

Just some cleanups around policy checks that came up during review.
The code is still not productive.
core: don't allow enabling if unit is masked
man: mention docker as type of virtualization
NEWS: update for 217
unit: move UnitDependency to unit-name
systemctl: add add-wants and add-requires verbs
note on relative symlink in os-release
nspawn: copy /dev/net/tun from host

This enables tuntap support in the container (assumning the necessary capabilities are in place).