remove complex rd modeling.

The affect on quality was minimal.  Less than .1%, various sets
yt ( +.15%), derf (-.1%), hd ( -.1% ), std hd(-.15%)...

The affect on speed of encode at speed -5 was substantial ( ~3% ).

Change-Id: I8903346fbae0c35f5b9ea20f81fdd239ae81247d