databases/mysql56-{client, server}: Update to latest release 5.6.44
This update includes
Bugfix:

• InnoDB: The INDEX_LENGTH value in INFORMATION_SCHEMA.TABLES was not updated when adding an index
• MySQL 5.6 did not build with maintainer mode enabled with GCC 7
• A damaged mysql.user table could cause a server exit
• mysqladmin shutdown did not wait for mysqld to shut down

More info: https://dev.mysql.com/doc/relnotes/mysql/5.6/en/news-5-6-44.html

Security Fix:
CVE-2019-1559, CVE-2018-3123 and other fixes.
More info: https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html#AppendixMSQL<Paste>

PR: 237399
Reported by: Brent Busby <brent@jfi.uchicago.edu>
Sponsored by: The FreeBSD Foundation