[libnotify] Non-fast-forward update to branch wip/notify-error-code

[Ray Strode <halfline src gnome org>]

The branch 'wip/notify-error-code' 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:

  f102f3d... notify-send: give failing exit code if showing notification

Commits added to the branch:

  771bbb5... notify-send: Give failing exit code if showing notification