The custom LCG is based on the POSIX recommend constants for a 16-bit
rand(). This implementation uses less computation than typical standard
library procedures which have been extended for 32-bit support, is
guaranteed to be reentrant, and identical everywhere.
Change-Id: I3140bbd566f44ab820d131c584a5d4ec6134c5a0
Ref: http://pubs.opengroup.org/onlinepubs/9699919799/functions/rand.html
Account for rounding in distortion calculation in k-means;
carry out rounding before duplicates removal of base colors;
replace numbers with macros;
use prefix increment.
Slight coding gain (<0.1%) on screen_content testset.
Change-Id: Ie8bd241266da6b82c7b2874befc3a0c72b4fcd8c
Add palette mode for keyframe luma channel. Palette mode is enabled
when using "--tune-content=screen" in encoding config parameters.
on screen_content testset: +6.89%
on derlr : +0.00%
Design doc (WIP):
https://goo.gl/lD4yJw
Change-Id: Ib368b216bfd3ea21c6c27436934ad87afdaa6f88
