I spent 4 hours on work and 12 hours of testing to try to find
the reason for aria crashing in recovery when starting a new test,
in which case the 'data directory' should be a copy of "install.db",
but aria_log.00000001 content was not correct.

The following changes are mostly done to make it a bit easier to find out
more in case of future similar crashes:

- Mark last_checkpoint_lsn volatile (safety).
- Write checkpoint message to aria_recovery.trace
- When compling with DBUG and with HAVE_DBUG_TRANSLOG_SRC,
  use checksum's for Aria log pages. We cannot have it on by default
  for DBUG servers yet as there is bugs when changing CRC between
  restarts.
- Added a message to mtr --verbose when copying the data directory.
- Removed extra linefeed in Aria recovery message (cleanup)