Build view list for all outputs at once
!1285 (merged) wants a compositor wide dirty bit for the view list, but then we have the common problem of the first output repaint damaging state (the dirty bit) the following output repaints might need.
So let's rework these bits so we don't have to pass an output to weston_compositor_build_view_list() at all, and calling it for any output updates for all outputs.