Forward-port surface dithering from CM10.1

This allows the use of 16-bit color displays without excessive color
banding;

Change-Id: Icb469b9cb4beb686516c60bb576dbd0a73f505e0
Merge tag 'android-4.3_r2.2' of https://android.googlesource.com/platform/frameworks/native into cm-10.2

Android 4.3 release 2.2

Change-Id: If9463fdc227b5fc97450a3ba94da815af6d9e657
Merge remote-tracking branch 'cm/cm-10.2' into jb3