This option results in allowing all login attempts without asking for
credentials. The name is confusing, but rather than rename it, we will
remove it, since it seems like a feature that no one would want.
* gnu/services/xorg.scm (<gdm-configuration>): Remove 'allow-root?'.
(gdm-pam-service): Do not use 'gdm-configuration-allow-root?'.
Signed-off-by: Danny Milosavljevic <dannym@scratchpost.org>