Revert "Turn off CONFIG_LOWBITDEPTH by default"
Revert "Turn off CONFIG_LOWBITDEPTH by default"

This reverts commit 155120f44aad2fce30f5a8a4ba2a15653e0e2f8f.

Reason for revert: allow time to investigate and fix #1563

BUG=aomedia:1563

Change-Id: I14818e143bc7b91ee5efb10a892a12f89827e297

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom