tty: Use SIGUSR1 for both enter and leave signals
tty: Use SIGUSR1 for both enter and leave signals

Now that we track has_vt, we can use the same handler for both enter and leave.

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