cli: use strerror to report signal error
RateControl bug fixes for frame parallelism

1. Added lastRceq in ratecotrol structure and copied the value into thread local rate control entry obj
so that Bframes can get latest lastRceq value.

2. Added framesDone state - to maintain a serial order of frames in RateCotrol to get a correct estimate of wantedBits.
tuned up ABR logic to better adapt for frame parallelism

 Rate control needs to be more aggressive based on actual ecoded bits cost rather than estimated costs from
 concurrent threads .Tuned up some parameters to effect this idea.