[rtslib-fb] Ensure internal buffers are flushed when saveconfig.json is written to disk.  A power-outage, unexpected reboot, etc can lead to zero byte file after a saveconfig.
[rtslib-fb] Ensure internal buffers are flushed when saveconfig.json is written to disk.  A power-outage, unexpected reboot, etc
can lead to zero byte file after a saveconfig.

Signed-off-by: Jon Magrini <a9bc82eb578bab0893cc51ff2517ca067e6bc386@redhat.com>

agrover/rtslib-fb,cvubrugier/rtslib-fb