[gtk+] Created tag 3.22.15

[Matthias Clasen <matthiasc src gnome org>]

The unsigned tag '3.22.15' was created.

Tagger: Matthias Clasen <mclasen redhat com>
Date: Thu May 11 15:46:57 2017 -0400

    3.22.15

Changes since the last tag '3.22.14':

Lapo Calamandrei (2):
      Adwaita: restyle entry-tag
      Adwaita: regenerate the css

Matthias Clasen (2):
      Revert "listbox: Properly remove placeholders"
      3.22.15

Timm Bäder (1):
      listbox: Manually unparent placeholder in dispose