Otherwise the tests will fail with:
INVALID: process 975: D-Bus library appears to be incorrectly set up; failed to read machine uuid: UUID file '/etc/machine-id' should contain a hex string of length 32, not length 0, with no other text
INVALID: See the manual page for dbus-uuidgen to correct this issue.
Upstream Arch now updated to Qt 5.6 (which means it works with Xvfb), and using
debug packages means the image is a lot bigger and builds slower, so let's use
the normal packages from [extra].
