Even Ubuntu 16.04 has automake 1.11.
Now that we no longer cater to automake 1.9, drop the comment
as well as the -Wno-obsolete option, since it does not seem to generate
any warnings anymore.
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>