[gtk] (6 commits) Non-fast-forward update to branch wip/otte/cairo-context

[Benjamin Otte <otte src gnome org>]

The branch 'wip/otte/cairo-context' 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:

  2928f46... gdk: Add Cairo context implementations for all backends
  3b68e81... gdk: Remove unused GL setting
  ae180e4... cairocontext: Turn cairo_create() function into a vfunc
  f50a6dc... surface: Fold function into only user
  89e61b9... gdk: Remove GDK_DEBUG=cairo-image
  1ac4844... x11: Move implementation of Cairo context backends

Commits added to the branch:

  af18935... gdk: Add Cairo context implementations for all backends
  4abc47c... gdk: Remove unused GL setting
  21d36f3... cairocontext: Turn cairo_create() function into a vfunc
  0d824eb... surface: Fold function into only user
  1f87114... gdk: Remove GDK_DEBUG=cairo-image
  9bd5a16... x11: Move implementation of Cairo context backends