MDEV-27107 prevent two mariadb-upgrade running in parallel
MDEV-27279 mariadb_upgrade add --check-if-upgrade-is-needed /
           restrict tests to major version

Code is based of pull request from Daniel Black, but with a several
extensions.

- mysql_upgrade now locks the mysql_upgrade file with my_lock()
  (Advisory record locking). This ensures that two mysql_upgrades
   cannot be run in parallel.
- Added --check-if-upgrade-is-needed to mysql_upgrade. This will return
  0 if one has to run mysql_upgrade.

Other changes:
- mysql_upgrade will now immediately exit if the major version and minor
  version  (two first numbers in the version string) is same as last run.
  Before this change mysql_upgrade was run if the version string was different
  from last run.
- Better messages when there is no need to run mysql_upgrade.
- mysql_upgrade --verbose now prints out a lot more information about
  the version checking.
- mysql_upgrade --debug now uses default debug arguments if there is no
  option to --debug
- "MySQL" is renamed to MariaDB in the messages
- mysql_upgrade version increased to 2.0

Notes
Verifying "prevent two mariadb-upgrade running in parallel" was
done in a debugger as it would be a bit complex to do that in mtr.

Reviewer: Danial Black <daniel@mariadb.org>