compositor-drm: Support output scaling
compositor-drm: Support output scaling

If you specify e.g. scale=2 in an output section in weston.ini
we scale all modes by that factor.

We also correctly scale cursor positioning, but ATM there is no
scaling of the cursor sprite itself.

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