am fbea2209: Merge "Remove uses of libcxx.mk."

* commit 'fbea2209c0b8037fe3234a994d52339c741ef74a':
  Remove uses of libcxx.mk.
tree: a6a58ee3e917fb246b6c570eb87acc77a16f1d89
  1. keystore/
  2. keystore-engine/
  3. softkeymaster/