configure.ac: The drm backend no longer requires EGL
configure.ac: The drm backend no longer requires EGL

We can run with just the pixman renderer and 'dumb' kms buffers.

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