Deployment on Windows doesn't work

attached a simple test-project for mingw.
1. windeployqt doesn't copy the needed "audio" plugin for QTMultimedia
2. when adding manually, deployment simply doesn't work, crashes on fresh computer, probably on platform plugin like with 5.2.1
3. manually creating qt.conf doesn't seem to have any influence

Please tell us how to make deployment work on this very very basic app.
The first audio input device name has to be shown in the messagebox.