[mutter] Non-fast-forward update to branch wip/carlosg/rt-scheduler

[Carlos Garnacho <carlosg src gnome org>]

The branch 'wip/carlosg/rt-scheduler' 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:

  ea0a998... backends: Externalize the post-init backend phase
  f2cf718... backends: Shuffle backend initialization
  ba5cbb9... core: Move unix signal handler later in the process
  e87515e... core: Drop all capabilities on initialization
  1bd9775... core: Set a SCHED_RR scheduler priority on Wayland sessions

Commits added to the branch:

  b2f6d46... backends/native: Add rt-scheduler experimental key to set R