[mutter] (26 commits) Non-fast-forward update to branch wip/nielsdg/cogl-clear-object

[Niels De Graef <nielsdg src gnome org>]

The branch 'wip/nielsdg/cogl-clear-object' 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:

  862b82b... cogl/object: add cogl_clear_object utility function

Commits added to the branch:

  740c229... build: Don't hardcode the path of python3 (*)
  aecf588... shadow-factory: Replace implicit API by explicit counterpar (*)
  605f35d... shadow-factory: Receive CoglFramebuffer (*)
  dd82fbe... clutter-stage: Replace cogl_clear by cogl_framebuffer_clear (*)
  c1b6184... clutter-stage: Pass framebuffer to read pixels from (*)
  203725b... clutter-actor: Remove cogl_rectangle from pick() (*)
  4c3d9fc... clutter-*-effect: Remove cogl_rectangle() (*)
  cabcad1... clutter-text: Replace cogl_rectangle() (*)
  a227e40... clutter-wayland-surface: Remove cogl_rectangle() (*)
  fcd1ff9... clutter-texture: Remove cogl_rectangle_with_texture_coords( (*)
  0304433... clutter-rectangle: Remove cogl_rectangle() (*)
  c585b21... gpu: Drop unused declaration (*)
  91d4f30... gpu/kms: Add identifier (*)
  4bc6a64... backends/native: Use the connector_id rather than winsys_id (*)
  5e00531... output: Turn winsys_id into a uint64_t (*)
  fb8dc91... output/kms: Make winsys_id unique (*)
  791bec3... display: Make lack of required X extensions a fatal error (*)
  97230a2... clutter/evdev: Use `clutter_event_set_device()` (*)
  ac6039b... clutter: Keep a device reference with events (*)
  4aa1e22... remote-desktop: Do not leak the virtual touchscreen (*)
  cbbd6d7... renderer/native: use DRM formats for dumb buffers (*)
  8c4743e... renderer/native: store dumb FB format (*)
  d4bea60... renderer/native: use cogl for CPU copy path (*)
  1c044a8... renderer/native: remove meta_renderer_native_gles3_read_pix (*)
  63a6ead... wayland-dma-buf: doc the odd format mapping (*)
  081842b... cogl/object: add cogl_clear_object utility function

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