Merge "Revert "Revert "Switch "system/core/base" ref to "system/libbase"""" am: 30d70441e5

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

Change-Id: Ib4c3d90835e2b7c82f157fb57ceeafea39beaf9e