[mutter] (6 commits) Non-fast-forward update to branch wip/carlosg/x11-selection-allow-clear

[Robert Mader <rmader src gnome org>]

The branch 'wip/carlosg/x11-selection-allow-clear' 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:

  825442c... x11: Clear X11 selection source after unsetting owner
  f8adb12... x11: Generalize x11 selection owner checks
  49f6e96... x11: Allow X11 clients to clear the selection

Commits added to the branch:

  551a57e... Add read-only anonymous file abstraction MetaAnonymousFile (*)
  988da21... wayland/keyboard: Use MetaAnonymousFile to share keymap fil (*)
  efb0add... tests/wayland: Add a test for meta-anonymous-file (*)
  94b3c33... x11: Clear X11 selection source after unsetting owner
  a7e63be... x11: Generalize x11 selection owner checks
  5671f0a... x11: Allow X11 clients to clear the selection

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