am c3115b9e: vold: Logging to catch when the disk checker crashes (could happen due to a really messed up card)

Merge commit 'c3115b9ec2f9bc07e6ffd7d7bb7338415822c338'

* commit 'c3115b9ec2f9bc07e6ffd7d7bb7338415822c338':
  vold: Logging to catch when the disk checker crashes