mysql57: updated to 5.7.42

Changes in MySQL 5.7.42

Functionality Added or Changed

Important Change: The linked OpenSSL library for MySQL Server has been updated to version 1.1.1t. Issues fixed in OpenSSL version 1.1.1t are described at https://www.openssl.org/news/cl111.txt.

The linked curl library for MySQL Server (Enterprise Edition) has been updated to version 7.88.1.

Bugs Fixed

InnoDB: Prevent online DDL operations from accessing out-of-bounds memory.

Replication: Some binary log events were not always handled correctly.

Replication: Setting binlog_order_commits to OFF could lead to a missed GTID in the next binary log file's Previous_gtids event.

Our thanks to Yewei Xu and the Tencent team for the contribution.

A client setting the character set to an impermissible client character set (ucs2, utf16, utf16le, or utf32) could cause unexpected behavior when the client used an authentication plugin.

The scope of the connect_timeout limit was extended to full-packet reads.

Using --single-transaction with mysqldump version 5.7.41 required either the RELOAD or FLUSH_TABLES privilege. This requirement now applies only when both gtid_mode=ON (default OFF) and with --set-gtid-purged = ON|AUTO (default AUTO).

(adam)