compositor-drm: cast surface to EGLNativeWindowType
compositor-drm: cast surface to EGLNativeWindowType

gl_renderer_output_create expects `window_for_legacy' variable to be of
type EGLNativeWindowType, not EGLNativeDisplayType. This variable is
used later in eglCreateWindowSurface().

Signed-off-by: Dawid Gajownik <158b9a61e3d4d82c23fe617ac4e66be51690b385@gmail.com>
Reviewed-by: Pekka Paalanen <0f6ae7001e34c37b02fb2c1c2573ddf8f442136a@collabora.co.uk>

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