dirty hack to get qt4 building for the time being

Summary:
apparently we don't build with c++11 by default on qt4, so the new
for just implodes. easy way out: if-else

qt4 is about to get removed anyway

Test Plan: I'll say three hail marys

Reviewers: dvratil, broulik

Reviewed By: broulik

Differential Revision: https://phabricator.kde.org/D22377