[mutter] (16 commits) Non-fast-forward update to branch gbsneto/pick-culling

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

The branch 'gbsneto/pick-culling' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  5ee5e4e... clutter/pick-stack: Add autoptr support
  135a1c8... clutter/stage: Remove cached pick mode
  2bc6f6b... clutter/pick-context: Store point and ray on construction
  7ace7b5... clutter/paint-volume: Add new API to convert to graphene_bo
  f9fa3cb... clutter/actor: Invalidate last paint volume on absolute geo
  406452b... clutter/actor: Cull out when picking

Commits added to the branch:

  b1700c3... clutter/actor: Remove two unused functions in private heade (*)
  8711d8d... backend: Keep a refcount on backend's current_device (*)
  a77e1f2... drm-buffer-gbm: Clear framebuffer with g_clear_object (*)
  c7a0ab3... background-content: ceilf the actor size instead of roundf (*)
  5ab187d... README: Add link to wiki (*)
  8fb30e6... README: Elaborate coding style and commit message guideline (*)
  232dcad... ci: Run coverage target by default (*)
  ebe8cd3... cursor-tracker: Check if coordinates are NULL (*)
  aff14ea... cursor-tracker: Check for NULL coordinates before retrievin (*)
  514b2ff... cursor-tracker: Get the GDK (X11) pointer position in float (*)
  e8840a4... clutter/pick-stack: Add autoptr support
  5dd173b... clutter/stage: Remove cached pick mode
  8798493... clutter/pick-context: Store point and ray on construction
  bda446f... clutter/paint-volume: Add new API to convert to graphene_bo
  b16d796... clutter/actor: Invalidate last paint volume on absolute geo
  fad5b75... clutter/actor: Cull out when picking

(*) This commit already existed in another branch; no separate mail sent