[evince] Non-fast-forward update to branch fix_criticals_label_absence

[Germán Poo-Caamaño <gpoo src gnome org>]

The branch 'fix_criticals_label_absence' 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:

  42366c3... don't set label property with a NULL value

Commits added to the branch:

  5d9c3d6... backends: Handle labels as optional on markup annotations