Merge changes Iec369a50,I3f9f8d56,I78959464,I72ea858e

* changes:
  logd: instrument tests better for failure
  liblog: log_time add explicit to some constructors.
  logd: iterator corruption paranoia
  logd: regression in handling watermark boundary.
tree: 89f0d34efb54080748dc53ad9cea2cf7729b92b7
  1. liblog/
  2. logcat/
  3. logd/
  4. logwrapper/