log fs_stat from fs_mgr and mount_all time

- fs_mgr reports fs_stat int value during bootup when mounting
  an ext4 partition.
- This includes information like:
  if previous shutdown was clean
  if e2fsck has fixed any fs issue
  if any mounting or quota related operations has failed.
- Each information is set as flag. Flag definitions are avaiable from
  FsStatFlags in system/core/fs_mgr/fs_mgr.cpp
- log ro.boottime.init.mount_all.[early|default|late] which represent
  time duration for each mount stage. Depending on device's config, some of
  these stages may not exist. So do not log if value is 0, which means not existing.

bug: 32246772
bug: 35949600
bug: 35329915

Test: manual, check log after boot-up.

Change-Id: I4ceca88776119d88d5352d6793be122e82688279