yad: needs gtk3-x11

Doesn't build with broadway or wayland since it wants the X-variant of
gdk. Fixes:
http://autobuild.buildroot.net/results/91d/91dc6ab749f967ae046f856f3f592d5a548499c6/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>