Merge changes from topic "unencrypted-dirs-q" into qt-dev

* changes:
  [RESTRICT AUTOMERGE] Log to EventLog on prepareUserStorage failure
  [RESTRICT AUTOMERGE] Ignore errors preparing user storage for existing users
  [RESTRICT AUTOMERGE] UserDataPreparer: reboot to recovery for system user only
  [RESTRICT AUTOMERGE] UserDataPreparer: reboot to recovery if preparing user storage fails
  [RESTRICT AUTOMERGE] StorageManagerService: don't ignore failures to prepare user storage
  Check user unlocked before write to /data/system_ce/0/snapshots