[oe] [meta-gnome][PATCH v02 3/3] dconf: make gtk+3 dependency optional

[andreas.kling at gmail.com]

many thanks for your review.
no idea how I only recognized rdepends in base class.

v03
remove duplicated depends to gtk+3
rebase from master to master-next

v02
fix typo

[oe] [meta-gnome][PATCH v03 1/3] dconf: depends on dbus
[oe] [meta-gnome][PATCH v03 2/3] dconf: fix bash completion in wrong
[oe] [meta-gnome][PATCH v03 3/3] dconf: make gtk+3 dependency