Remove RingBuffer.hxx #776
Description
There seems to be two classes with the same functionality, DeviceBuffer.hxx and RingBuffer.hxx.
We could probably remove RingBuffer.hxx. It seems it is used in two places.
Stream.hxx which is code that was never finished and doesn't even compile.
Pipe.hxx which should likely rather utilize the DeviceBuffer since it should really have select support.