use centralized handling of QT_BUILD_PARTS
use centralized handling of QT_BUILD_PARTS

Change-Id: Ib50f58e03eca48212cb05389257e248d44ca7ebb
Reviewed-by: Rohan McGovern <d75463945f40a9669160a73cef2843e56b22c602@nokia.com>

richardmg/qtsensors,richardmg/qtsensors,mer-qt/qtsensors,kobolabs/qtsensors,kobolabs/qtsensors,mer-qt/qtsensors,mer-qt/qtsensors,richardmg/qtsensors,richardmg/qtsensors,richardmg/qtsensors,kobolabs/qtsensors,mer-qt/qtsensors,mer-qt/qtsensors,kobolabs/qtsensors