desktop-shell: Damage the black view when we remove it
desktop-shell: Damage the black view when we remove it

We should be using weston_view_unmap() here, or maybe just destroying the
black view, but let's do a minimal, safe fix for the 1.5 release.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=78501

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