Merge "Revert "Revert "Switch "system/core/base" ref to "system/libbase"""" am: 30d70441e5 am: 95c0590278 am: ae1eb97bf6 am: 3283dae0cc

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1476616

Change-Id: Ie1246d0731bdaf1920cfb68941806e5e3d88d48d