[Regression] Nvidia-prime 0.7: No dependency on SDDM

-> Depends: lightdm (>= 1.9.1) | gdm | kdm,

The new version 0.7 does no longer depend on sddm. This pulls in lighdm together with many gnome packages.

$sudo apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... The following package was automatically installed and is no longer required:
  qemu-slof
Use 'apt-get autoremove' to remove it.
Done
The following NEW packages will be installed:
  apg avahi-utils cheese-common cups-pk-helper dconf-cli evolution-data-server evolution-data-server-common evolution-data-server-online-accounts geoclue
  geoclue-ubuntu-geoip gir1.2-gnomebluetooth-1.0 gir1.2-gnomekeyring-1.0 gir1.2-ibus-1.0 gir1.2-notify-0.7 gir1.2-packagekitglib-1.0 gkbd-capplet
  gnome-bluetooth gnome-control-center-shared-data gnome-desktop3-data gnome-icon-theme-symbolic gnome-menus gnome-power-manager gnome-screensaver
  gnome-session-bin gnome-settings-daemon-schemas gnome-user-guide gnome-user-share gsettings-ubuntu-schemas gstreamer1.0-clutter gvfs-backends hwdata
  ibus indicator-applet indicator-bluetooth indicator-datetime indicator-keyboard indicator-messages indicator-power indicator-session indicator-sound
  libaccount-plugin-1.0-0 libaccount-plugin-generic-oauth libaccount-plugin-google libaccounts-qt5-1 libcamel-1.2-49 libcdio-cdda1 libcdio-paranoia1
  libcheese-gtk23 libcheese7 libclutter-1.0-0 libclutter-1.0-common libclutter-gst-2.0-0 libclutter-gtk-1.0-0 libcogl-common libcogl-pango20
  libcogl-path20 libcogl20 libebackend-1.2-7 libebook-1.2-14 libebook-contacts-1.2-0 libecal-1.2-16 libedata-book-1.2-20 libedata-cal-1.2-23
  libedataserver-1.2-18 libgdata-common libgdata19 libgee2 libgeocode-glib0 libgnome-bluetooth11 libgnome-desktop-3-10 libgnome-menu-3-0
  libgnomekbd-common libgnomekbd8 libgoa-1.0-0b libgoa-1.0-common libgtop2-10 libgtop2-common libgweather-3-6 libgweather-common libido3-0.1-0
  liblightdm-gobject-1-0 libnm-gtk-common libnm-gtk0 liboauth0 libpackagekit-glib2-16 libpanel-applet0 libsignon-extension1 libsignon-glib1
  libsignon-plugins-common1 libsignon-qt5-1 libtimezonemap-data libtimezonemap1 libunity-control-center1 libunity-settings-daemon1 liburl-dispatcher1
  libwacom-common libwacom2 libxklavier16 libyelp0 lightdm mousetweaks nautilus-data network-manager-gnome python-gtk2 python-notify
  python3-aptdaemon.pkcompat python3-cairo python3-lxml python3-smbc python3-xdg session-migration signon-keyring-extension signon-plugin-oauth2
  signon-ui signon-ui-service signon-ui-x11 signond system-config-printer-common system-config-printer-gnome ubuntu-system-service ubuntu-touch-sounds
  unity-control-center unity-control-center-signon unity-greeter unity-settings-daemon yelp yelp-xsl
The following packages will be upgraded:
  nvidia-prime
1 upgraded, 127 newly installed, 0 to remove and 0 not upgraded.
Need to get 29,6 MB of archives.
After this operation, 124 MB of additional disk space will be used.