Merge changes I5731d640,Ia874b57a

* changes:
  logd: make LogBuffer an interface
  logd: refactor LastLogTimes a bit
tree: 7526490a3d541a44f7a317dfac3762ceb6ed7fc1
  1. liblog/
  2. logcat/
  3. logd/
  4. logwrapper/