Support QJson 0.7 which is still used in Precise
Support QJson 0.7 which is still used in Precise

This version lacks a QJson::Serializer::serialize(const QVariant&, bool*),
so emulate it by checking whether the returned QByteArray isNull.

http://buildbot.clementine-player.org/builders/Ubuntu%20Precise%2064-bit/builds/68/steps/compile/logs/stdio

gpodder/libmygpo-qt,gpodder/libmygpo-qt