The theme uses svg files. If libsvg-gtk isn't available lxdm
still runs, but throws a bunch of pixbuf errors.

Signed-off-by: Dan McGregor <dan.mcgregor@usask.ca>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>