[mutter] (2 commits) Non-fast-forward update to branch wip/nielsdg/n-planes

[Niels De Graef <nielsdg src gnome org>]

The branch 'wip/nielsdg/n-planes' 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:

  aa2b2a2... cogl: Add a notion of pixel format planes

Commits added to the branch:

  97010ac... meta: Move private defines to a private header (*)
  c21ed06... cogl: Add a notion of pixel format planes

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