/etc/init.d/swupdate: pass $SWUPDATE_EXTRA_ARGS to daemon
The idea is that /etc/default/swupdate now can be used to set
$SWUPDATE_EXTRA_ARGS. I plan to use this for passing --select=... to
swupdate, based on some shell logic.
Signed-off-by: Bjørn Forsman <bjorn.forsman@gmail.com>