Regretfully, the parameter innodb_log_checksums was introduced
in MySQL 5.7.9 (the first GA release of that series) by
mysql/mysql-server@af0acedd885eb7103e319f79d25fda7386ef1506
which partly replaced a parameter that had been introduced in 5.7.8
mysql/mysql-server@22ba38218e1d76c24f69b5a5595ad3bf5933acb0
as innodb_log_checksum_algorithm.

Given that the CRC-32C operations are accelerated on many processor
implementations (AMD64 with SSE4.2; since MDEV-22669 also on IA-32
with SSE4.2, POWER 8 and later, ARMv8 with some extensions)
and by lookup tables when only generic SISD instructions are available,
there should be no valid reason to disable checksums.

In MariaDB 10.5.2, as a preparation for MDEV-12353, MDEV-19543 deprecated
and ignored the parameter innodb_log_checksums altogether. This should
imply that after a clean shutdown with innodb_log_checksums=OFF one
cannot upgrade to MariaDB Server 10.5 at all.

Due to these problems, let us deprecate the parameter innodb_log_checksums
and honor it only during server startup.
The command SET GLOBAL innodb_log_checksums will always set the
parameter to ON.