Gnome-open has been deprecate for some time.  xdg-open replaces it.

Change-Id: I7fc0f32a1f2fbadbe3d1cee58d0089213665c3a5
Reviewed-on: https://gerrit.libreoffice.org/20347Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>