Fix for MDEV-11174: A GCM encrypted ciphertext must contain an authentication tag with AES_BLOCK_SIZE length, so we need to check that the length of ciphertext is at least AES_BLOCK_SIZE.
Fix for MDEV-11174:
A GCM encrypted ciphertext must contain an authentication tag with AES_BLOCK_SIZE length, so we need to check that the length of ciphertext is at least AES_BLOCK_SIZE.

natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2