As with CRTC state, variable connector state is now fetched via the
MetaKmsConnector. The existance of a connector state is equivalent of
the connector being connected. MetaOutputKms is changed to fetch
variable connector state via MetaKmsConnector intsead of KMS directly.
The drmModeConnector is still used for constructing the MetaOutputKms to
find properties used for applying configuration.
https://gitlab.gnome.org/GNOME/mutter/issues/548https://gitlab.gnome.org/GNOME/mutter/merge_requests/525