lupdate doesn't parse resource files if passed via json project's description file

When lupdate parses sources provided via JSON project's description then file resources files (*.qrc) are not scanned. 

This is quite big problem because cmake's qt_add_translations internally generates json files with sources list and passes it to lupdate.  With current behavior its not possible to use cmake's target update_translations if some file are in qrc resource (which is kind of convenient for qml files).