weston.ini: Move binding-modifier to shell section.
weston.ini: Move binding-modifier to shell section.

The variable has no effect as part of the screensaver section.

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