Prioritize XClip for clipboard on linux
Prioritize XClip for clipboard on linux

 closes #5792
matham/kivy,rnixx/kivy,inclement/kivy,inclement/kivy,rnixx/kivy,kivy/kivy,matham/kivy,matham/kivy,kivy/kivy,inclement/kivy,LogicalDash/kivy,LogicalDash/kivy,akshayaurora/kivy,akshayaurora/kivy,LogicalDash/kivy,matham/kivy,rnixx/kivy,akshayaurora/kivy,LogicalDash/kivy,kivy/kivy