OPT_PAGE_CHECKSUM is ignored if innodb_encrypt_log=ON

In the merge of the MDEV-18976 implementation, a logical conflict with MDEV-14425 was resolved incorrectly. The log record parser is reading the contents of an OPTION record without attempting to decrypt it. Unless the first payload octet OPT_PAGE_CHECKSUM happens to encrypt to itself, these record will be ignored. By design, all OPTION records can be ignored without breaking anything.

In debug-instrumented builds, InnoDB is writing OPT_PAGE_CHECKSUM records so that some recovery errors can be caught better. This bug causes that to be mostly a wasted effort when innodb_encrypt_log=ON.