message: Discard debug messages after starting the frame capture
  * This prevents us from serialising debug messages caused by the
  initial state preparation accidentally.
diff: @@ -1282,6 +1282,9 @@ void WrappedID3D12Device::StartFrameCapture(void *dev, void *wnd)
  RDCDEBUG("Attempting capture");
  m_FrameCaptureRecord->DeleteChunks();
  + // fetch and discard debug messages so we don't serialise any messages of our own.
  + (void)GetDebugMessages();
  +
  {
  CACHE_THREAD_SERIALISER();
  