mysql-8.0 regression

USN-4441-1 fixed vulnerabilities in MySQL. The new upstream version
changed compiler options and caused a regression in certain scenarios. This
update fixes the problem.

Original advisory details:

Multiple security issues were discovered in MySQL and this update includes
new upstream MySQL versions to fix these issues.

MySQL has been updated to 8.0.21 in Ubuntu 20.04 LTS. Ubuntu 16.04 LTS and
Ubuntu 18.04 LTS have been updated to MySQL 5.7.31.

In addition to security fixes, the updated packages contain bug fixes, new
features, and possibly incompatible changes.

Please see the following for more information:

https://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-31.html

https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-21.html

https://www.oracle.com/security-alerts/cpujul2020.html