Fix build in C++98 mode: template typenames must not be local

qgltf.cpp:1990:38: error: template argument for ‘template<class Key, class T> class QHash’ uses local type ‘GltfExporter::exportTechniques(QJsonObject&, const QString&)::ProgramNames’

Change-Id: Ic747cc2ab45e4dc6bb70ffff143844dc7120e571
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>