infos[]: Allocate enough entries to accommodate all keys from both
checkpoint pages.
infos_used: The size of infos[].
get_crypt_info(): Merge to the only caller, log_crypt_101_read_block().
log_crypt_101_read_block(): Do not validate the log block checksum,
because it will not be valid when upgrading from MariaDB 10.1.10.
Instead, check that the encryption key exists.
log_crypt_101_read_checkpoint(): Append to infos[] instead of overwriting.
8a42ad7a5d