[kde-base/kwin] Add dev-qt/qtgraphicaleffects as runtime dependency

Without dev-qt/qtgraphicaleffects installed, Aurorae based kwin
decorations can't be rendered.

Package-Manager: portage-2.2.10
Merge pull request #39 from eliasp/kwin-qtgraphicaleffects

[kde-base/kwin] Add dev-qt/qtgraphicaleffects as runtime dependency