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
diff --git a/build/cmake/aom_config_defaults.cmake b/build/cmake/aom_config_defaults.cmake
index 8b918ed..da51551 100644
--- a/build/cmake/aom_config_defaults.cmake
+++ b/build/cmake/aom_config_defaults.cmake
@@ -82,7 +82,7 @@
 set(CONFIG_COEFFICIENT_RANGE_CHECKING 0 CACHE NUMBER "Coefficient range check.")
 set(CONFIG_INSPECTION 0 CACHE NUMBER "Enables bitstream inspection.")
 set(CONFIG_INTERNAL_STATS 0 CACHE NUMBER "Codec stats.")
-set(CONFIG_LOWBITDEPTH 0 CACHE NUMBER "Enables 8-bit optimized pipeline.")
+set(CONFIG_LOWBITDEPTH 1 CACHE NUMBER "Enables 8-bit optimized pipeline.")
 set(CONFIG_REALTIME_ONLY 0 CACHE NUMBER "Support only realtime encodes.")
 set(CONFIG_SIZE_LIMIT 0 CACHE NUMBER "Limit max decode width/height.")
 set(CONFIG_SPATIAL_RESAMPLING 1 CACHE NUMBER "Spatial resampling.")