[mutter] (7 commits) Non-fast-forward update to branch wip/carlosg/fix-second-monitor-invalidations

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

The branch 'wip/carlosg/fix-second-monitor-invalidations' 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:

  260b434... clutter/cogl: Fix invalidation on non-primary monitors with
  5b09b87... Revert "clutter/cogl: Store empty clip regions for buffer a

Commits added to the branch:

  7c036c5... cogl: fix a compile warning (*)
  f4f7e31... cogl: Fix GLES2 fallback (*)
  6ee7c0f... cogl/egl: Warn when we fail to query a buffer age. (*)
  ee4638e... cogl/egl: Make surface current before querying buffer age (*)
  d47324e... cogl/egl: Explicitly initialize age variable (*)
  cf89e4d... clutter/cogl: Fix invalidation on non-primary monitors with
  6bfa61a... Revert "clutter/cogl: Store empty clip regions for buffer a

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