xdg-utils: update to latest git and ship xdg-terminal

gdm and gnome-session call xdg-terminal :(

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
xinput-calibrator: fix XDG launch

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>