gradle: Build fossDebug flavor by default.
gradle: Build fossDebug flavor by default.

abarisain/dmix,joansmith/dmix,hurzl/dmix,hurzl/dmix,0359xiaodong/dmix,joansmith/dmix,abarisain/dmix,jcnoir/dmix,jcnoir/dmix,0359xiaodong/dmix