message: fix ByteStreamBuffer
diff: @@ -70,21 +70,21 @@ protected:
  std::ios_base::seekdir dir,
  std::ios_base::openmode )
  {
  - // get absolute offset
  - off_type off = offset;
  + char* whence = eback();
  if (dir == std::ios_base::cur)
  {
  - off += gptr() - eback();
  + whence = gptr();
  }
  else if (dir == std::ios_base::end)
  {
  - off += egptr() - eback();
  + whence = egptr();
  }
  + char* to = whence + offset;
  // check limits
  - if (off >= (off_type)0 && off <= egptr() - eback())
  + if (to >= eback() && to <= egptr())
  {
  - setg(eback(), gptr() + off, egptr());
  + setg(eback(), to, egptr());
  return gptr() - eback();
  }
  