[mutter] (6 commits) Non-fast-forward update to branch wip/carlosg/clip-regions

[Carlos Garnacho <carlosg src gnome org>]

The branch 'wip/carlosg/clip-regions' 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:

  5867317... cogl: Add support for clipping regions
  c9adb17... clutter/cogl: Use regions for clipping if necessary
  5325dd0... compositor: Use redraw clip region to cull out children
  9135ae6... cogl: Drop unused struct field
  10906ff... clutter: Check updated devices with the current clip
  d48542e... clutter: Drop unused API

Commits added to the branch:

  0cd75b7... cogl: Add support for clipping regions
  7b13b78... clutter/cogl: Use regions for clipping if necessary
  9bced89... compositor: Use redraw clip region to cull out children
  76d6830... cogl: Drop unused struct field
  9204f78... clutter: Check updated devices with the current clip
  daaea9a... clutter: Drop unused API