Freeze exception for mutter and gnome-shell

[Jonas Ådahl <jadahl gmail com>]

I'd like to request a freeze break for mutter and gnome-shell to fix DND
on Wayland when going via the overview. It is an API/ABI addition,
moving some logic from gnome-shell to mutter, but the will only impact
gnome-shell. Impact outside of GNOME is most likely minimal, as mutter
changes the names of .so files this cycle.

The bug in question is:
https://bugzilla.gnome.org/show_bug.cgi?id=765003


Jonas