databases/mysql57-{client, server}: Update to latest release 5.7.26
This update includes:
Bugfix:

• InnoDB: Optimized internal temporary tables did not support in-place UPDATE operations
• InnoDB: A function called by a CREATE TABLE thread attempted access after free()
• InnoDB: The INDEX_LENGTH value in INFORMATION_SCHEMA.TABLES was not updated when adding an index
• The authentication_ldap_simple plugin could enforce authentication incorrectly

More info: https://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-26.html

Security Fix:
CVE-2019-2632, CVE-2019-1559, CVE-2018-3123, and other fixes.
More info: https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html#AppendixMSQL

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