tests/egl_ext_surface_compression: skip if Wayland display connection fails

This showed today (after the naming fix by @dh) in r300 CI failures https://gitlab.freedesktop.org/mesa/mesa/-/jobs/63918114. The test will currently crash if wl_display_connect fails (I'm assuming because there is no wayland server running 🤷 ), create_wayland_display returns 0 and we will later try to dereference it in get_wayland_native_display. So just add a skip...