weston: Don't ask for EGL depth buffer if not needed

This makes the compositor and demo clients work on the current nouveau
nvfx driver. Obviously does not fix any clients that actually want a
depth buffer, but this does allow more people to at least try wayland.

clients/simple-egl.c

@@ -100,7 +100,6 @@ init_egl(struct display *display)
 		EGL_GREEN_SIZE, 1,
 		EGL_BLUE_SIZE, 1,
 		EGL_ALPHA_SIZE, 1,
-		EGL_DEPTH_SIZE, 1,
 		EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
 		EGL_NONE
 	};