[Development] Enabling private features for separate modules

[Oswald Buddenhagen]

On Mon, Jun 19, 2017 at 12:52:12PM +0300, Alexander Volkov wrote:
> Hi,
> 
> I build qtwebengine as a separate module.
> What is the right way to enable system-ffmpeg feature?
>
you use

  qmake [usual qmake args] -- [configure args]