shell: Don't launch a new screensaver if the old one is still running
shell: Don't launch a new screensaver if the old one is still running

krezovic/weston,sir-murray/weston,Gnurou/weston,udoprog/weston,eyolfson/weston,jonnylamb/weston,kwm81/weston,krezovic/weston,jonnylamb/weston,Gnurou/weston,Tarnyko/weston-xdg_surface_present,udoprog/weston,xorgy/weston,Tarnyko/weston-xdg_surface_present,sir-murray/weston,giucam/weston,Fantu/compositor-spice,giucam/weston,Fantu/compositor-spice,mchalupa/weston,mchalupa/weston,Fantu/compositor-spice,eyolfson/weston,kwm81/weston,xorgy/weston