ptxd_make_world_clean: make sure ${pkg_xpkg_map} exists before using it

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
ptxdist: rework icecc setup

- make it work when building toolchains
- abort if the host compiler is a script (such as debian hardening wrapper)
  icecc cannot handle this and generates a broken environment

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
systemd: version bump 215 -> 216

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
image_working_dir: depend on world

The image_working_dir cannot be created until 'world' is done. Usually this
is not a problem because the image targets depend on 'world' first. With
-jeX image_working_dir may be executed too early and fail.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>