egl/x11_dri3: provide an authentication function

egl/x11_dri3: provide an authentication function

To support WL_bind_wayland_display an authentication function needs to be
provided but this was not being done for this platform as it's not strictly
necessary. However, as this isn't an optional function there's the potential
for a segfault to occur if authentication is mistakenly performed. Protect
against this by providing a function that prints an error.

Signed-off-by: Frank Binns <frank.binns@imgtec.com>
Reviewed-by: Axel Davy <axel.davy@ens.fr>