Print thread_id instead of pthread_self to error log
Print thread_id instead of pthread_self to error log

- Now we have same thread_id in general log, slow long and error log
  instead of a long meaningless thread number that may even change for
  one user.
- Align error and slow log header with output
- Extend thread_id with one number to handle nice printing up to ten
  million connections

natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2