[gtk+] (5 commits) Non-fast-forward update to branch wip/gl-texture

[Matthias Clasen <matthiasc src gnome org>]

The branch 'wip/gl-texture' 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:

  d03e3a2... wip: Add a gl texture implementation
  a4aaecb... Add private api to get at the gl texture data
  fc7668c... gsk: Handle GL textures properly
  9abe8ea... wip: convert gtkglarea to use snapshots
  0b982dd... fix error screen
  a066674... glarea: Always use textures
  ff65b02... Drop GtkGLArea::has-alpha
  d74bc7a... Recreate the GdkTexture every time
  9d9d692... Add a destroy notify to gl textures

Commits added to the branch:

  b366ea8... gdk: Add a gl texture implementation (*)
  31fcf5b... gsk: Handle GL textures (*)
  5711fb9... Convert gtkglarea to use snapshots (*)
  f3927f1... Drop GtkGLArea::has-alpha (*)
  fe7d078... Flip gl textures when used in the gl renderer

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