In the case one has an old Aria log file that ands with a Aria checkpoint
and the server restarts after next recovery, just after created a
new Aria log file (of 8K), the Aria recovery code would abort.
If one would try to delete all Aria log files after this (but not the
aria_control_file), the server would crash during recovery.

The problem was that translog_get_last_page_addr() would regard a log file
of exactly 8K as illegal and the rest of the code could not handle this
case.

Another issue was that if there was a crash directly after the log file
head was written to the next page, the code in translog_get_next_chunk()
would crash.

This patch fixes most of the issues, but not all. For Sanja to look at!

Things fixed:
- Added code to ignore 8K log files.
- Removed ASSERT in translog_get_next_chunk() that checks if page only
  contains the log page header.