meta-android: android-system: correctly kill service on shutdown

The android-system systemd service wasn't correctly killed on shutdown as it was hanging
when doing that the normal way with lxc-stop. To not let it block the systemd shutdown
process we're killing the main process now with SIGKILL.

Signed-off-by: Simon Busch <morphis@gravedo.de>

meta-android/recipes-core/android-system/android-system/android-system.service

@@ -6,9 +6,8 @@ Before=network.target ofono.service pulseaudio.service
 Type=simple
 ExecStart=/usr/bin/lxc-start -n android -l DEBUG -- /init
 ExecStartPost=/usr/bin/wait-for-android.sh
-# FIXME lxc-stop doesn't seem to work well so we're killing the main process instead
-# ExecStop=/usr/bin/lxc-stop -n android -k
-ExecStop=/bin/kill -KILL $MAINPID
+KillMode=process
+KillSignal=SIGKILL
 # Never kill the android system when we're on low memory
 OOMScoreAdjust=-1000